Silane functional stabilizers for extending long-term electrical power cable performance

ABSTRACT

Provided are methods for extending the life of in-service electrical cable having polymeric insulation, comprising injecting a dielectric enhancement fluid composition into the cable, wherein the composition comprises: (a) one or more organoalkoxysilane functional additives (voltage stabilizer-based, hindered amine light stabilizer (HALS)-based, and/or UV absorber-based); and (b) a catalyst suitable to catalyze hydrolysis and condensation of (a), the injected composition providing for rapid initial permeation of (a) into the insulation, and extended retention of subsequent condensation products of (a) in the insulation. Additionally provided are innovative silyl functional ferrocenes (e.g., containing a ferrocene moiety and a silyl function hydrolysable to silanol) having utility as functional voltage stabilizing additives in the methods.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/874,155, filed on Jul. 15, 2019, and 62/876,967, filed on Jul. 22,2019, which are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the method of enhancing and extendingthe life of underground cable insulation through the injection of fluidsand gels containing novel silane functional additives.

Description of the Related Art

Extensive networks of underground electrical cables are in place in manyparts of the industrialized world. Such underground distribution offersgreat advantage over conventional overhead lines in that it is notsubject to wind, ice or 20 lightning damage and is thus viewed as areliable means for delivering electrical power without obstructing thesurrounding landscape, the latter feature being particularly appreciatedin suburban and urban settings. Unfortunately, these cables (whichgenerally comprise a stranded conductor surrounded by a semi-conductingconductor shield, a polymeric insulation jacket, and an insulationshield), particularly those installed prior to 1995, often sufferpremature breakdown and do not attain their originally anticipatedlongevity of 30 to 40 years.

For medium and high voltage cables, dielectric breakdown is generallyattributed to so-called “treeing” phenomena (i.e., formation ofmicroscopic dendritic structures within the insulation material, fromwhich the descriptive terminology 30 derives), which lead to aprogressive degradation of the cable's dielectric strength.

Contrary to medium or high voltage cables, damage in the insulation of alow voltage cable, such as a distribution cable supplying a privatehome, which can result from improper installation, dig-ins, orinsulation degradation due to external factors (thermal, ultraviolet(UV), chemical exposure), does not necessarily lead to failure of theconnection. In medium- and high-voltage cable the electric fieldstrength within the insulation will cause an immediate breakdown,whereas in low-voltage cable the damaged cable can still withstand therelatively low field and the cable remains operational. However, at thedamaged location the conductor is exposed. Depending on the surroundingground properties, different degradation mechanisms, such as corrosion,can occur. These mechanisms can eventually result in failure of theconnection. (van Deursen, A.; Wouters, P.; Kruizinga, B.; Steennis, F.,“AC Induced Corrosion of Low Voltage Power Cables with AluminumConductors,” NACE International Corrosion Conference & Expo, 2018).Since replacing a failed section of underground cable can be a veryexpensive and involved procedure, there is a strong motivation on thepart of the electrical utility industry to extend the useful life ofexisting underground cables in a cost-effective manner.

In addition, underground electrical utilities also present fire and/orexplosion hazards proximate to areas of human habitation. For example,while conduits provide passageways between vaults for interconnectingelectrical cables, the conduits also allow air, gases, vapors, and waterto enter the interiors of the vaults. It is not unusual for suchunderground vaults and conduits to fill with water depending on thesurface topography, water table, and recent precipitation. Water alsoenters through the manhole cover. Water allows for electro-chemicalbreakdown of the insulation to occur through tracking of cables in ducts(i.e., electrical discharge along degraded insulation) and electricalequipment failures inside one or more of the vaults, which producehazardous concentrations of explosive and flammable gases within one ormore of the vaults. Because air can never be excluded entirely from avault, manhole events may result. Manhole events include both minorincidents (such as smoke or small fires) and/or major events (such assustained fires and explosions). At best, a minor incident is likely tocause an electrical power outage. At worst, a major event, such as anexplosion, can occasionally propel a manhole cover skyward causingproperty damage, injuries, and even death (United States PatentApplication Publication No. 20180363940, by Bertini, Glen J.; Songras,Donald R.). While the referenced patent application proposes methods toavoid manhole events, reducing the number of underground cable failureswill reduce their frequency.

A typical method for rejuvenating in-service medium and high-voltagepower cables operating at above about 5 kV comprises introducing a treeretardant fluid into the void space (interstitial void volume)associated with the strand conductor geometry. This fluid diffuses intothe insulation and fills the microscopic trees thereby augmenting theservice life of the cable. The fluid is generally selected from aspecific class of alkoxysilanes which can oligomerize within the cable'sinterstitial void volume, as well as within the insulation (Vincent, etal., in U.S. Pat. No. 4,766,011). This method and variations thereofemploying certain rapidly diffusing components U.S. Pat. Nos. 5,372,840and 5,372,841) have enjoyed commercial success for more than two decadesor so.

Alternatively, the problem of corrosion and tracking common inlow-voltage power cable systems operating below about 1 kV has beenattacked by excluding water from the cable's interior by filling theinterstices of the cable conductor with a dielectric gel whicheffectively acts as a “water block.” For example, see U.S. Pat. No.4,978,694, issued to Vincent and Meyer and references therein. While gelfilling of the cable prevents entry of water into the interstices andhelps prevent corrosion of the conductors, it does not addressdegradation of the polymeric insulation of the cable.

However, all the current methods known to applicants still do notdeliver the full potential of insulation longevity. For tree-retardantfluids, this is very likely due to the diffusion of these compounds outof the cable within 10 to 15 years after treatment, thereby againexposing the cable to the above-mentioned treeing phenomena (e.g., seeBertini, “Accelerated Aging of Rejuvenated Cables—Part I,” ICC, Sub. A,Apr. 19, 2005). For dielectric gels, the low voltage cable insulationdoes not receive additional protection against oxidation brought on bythermal, chemical or UV exposure that serve as points of water ingress.Thus, there is a continued desire on the part of the utility industry tofurther extend the reliable performance of treated cable, therebyimproving efficiency and reducing operating costs.

Electrical-treeing phenomena which occur in polymers such as low-densitypolyethylene (LDPE),) crosslinked polyethylene (XLPE), andethylene-propylene rubber (EPR) have been under study for many years.Several mechanisms have been proposed to explain electrical treeing ininsulation materials subjected to high electric fields. Among these are:(a) fatigue cracking due to Maxwell stress, (b) Joule heating that leadsto thermal decomposition, (c) high field-induced impact ionization, (d)hot electrons that can break polymer bonds, (e) space chargerecombinations that generate UV photons capable of severing polymerbonds, and (f) thermal cycling of polymer in the presence of waterleading to supersaturation of water in the polymer during the coolingportion the cycle which, upon condensation, mechanically tears voids inthe polymer and (d) hot electrons that can break polymer bonds.Mechanism (a) cannot be responsible for tree initiation because Maxwellinduced mechanical stresses produced in polyethylene (PE) cablesoperating at working stresses are only a fraction of the tensilestrength of the polymer. Mechanism (b) requires the preexistence of acavity within which partial discharges (PD) can occur, but tests withneedles in solids have shown that no initial void at the needle tip isrequired to start tree growth. Mechanisms (c) and (d) require that thecharge carriers in the polymer gain large energies from the electricfield. But since the mean free path of charges in PE is of the order ofa few molecular radii (5-20 Å), it is almost impossible for them tobecome hot enough to cause impact ionization or break bonds of thepolymer chain. Mechanism (e) occurs wherever water trees have formed.Mechanism (f) occurs wherever the load and thermal cycling is severeenough to induce supersaturation. However, in high-voltage cables,gradual degradation that leads to electrical-tree initiation occurs atelectrical fields much lower than the breakdown strength of thepolymeric insulation. Defects that are accidentally introduced into thepolymer during cable manufacture become points of high local stress andreduce insulation performance. Such points of high electrical stress areusually simulated in the laboratory by molding needles into the polymer.

To overcome the problem of electrical treeing, several solutions havebeen proposed thus far. For instance, McMahon, U.S. Pat. No. 4,206,260,proposes using LDPE or XLPE insulation with an amount of an alcohol of 6to 24 carbon atoms. Maloney, U.S. Pat. No. 3,499,791, discloses apolyethylene insulation containing an inorganic ionic salt of a strongacid and a strong zwitter-ion compound. Kato et al., U.S. Pat. No.3,956,420, discloses insulation comprising a polyolefin, a ferrocenecompound and a substituted quinoline compound. Additionally, a smallamount of polyhydric alcohol, dispersant, surfactant or unsaturatedpolymer or mixture thereof is used. MacKenzie, Jr., U.S. Pat. No.3,795,646, recommends the use of a silicone fluid in a crosslinkedpolyethylene composition.

Shimizu et al. (IEEE Trans. Electr. Insul. EI-14, 256 (1979) havereported that light is emitted at needle tips in LDPE subjected tohighly divergent fields at a cryogenic temperature (liquid nitrogen).Bamji et al. (Annual Report of 1982 Conference on Electrical Insulationand Dielectric Phenomena. IEEE Service Center, Piscataway, N.J., p.592), have discovered similar emissions at room temperatures. This lighthas been attributed to electroluminescence (EL) caused by chargeinjection into the polymer from the metallic point.

Ultraviolet (UV) radiation has been detected during tree initiation, theradiation occurring at needle tips embedded in low density polyethylene(LPDE). It is proposed that the UV radiation causes photo degradation ofthe polymer, i.e. the energy is dissipated as photons which break thepolymer and eventually create a micro cavity in which partial dischargescan occur and lead to tree propagation. It is important to note that theUV radiation detected in the conditions described herein has a range of400 to 200 nm.

Polymer additives such as antioxidants, UV absorbers and free radicalscavengers like HALS (Hindered Amine Light Stabilizers) have been usedin such formulations to retard radical and UV induced degradation. Priorart patents teach the use of several such additives to improve thelong-term efficacy of restorative fluids resulting in the followingbenefits:

-   -   a. Extended dwell time in the cable insulation,    -   b. Being at least five times more soluble than water in        polymeric insulation, these materials preferentially “wet” the        insulation, thereby greatly reducing the rewetting of the        insulation by water permeation,    -   c. Additives augment the density of the dielectric enhancement        fluid formulation in which they are incorporated, and this        translates into an increased supply of total fluid mass to        impart additional life-extension functionality into a given        interstitial volume, and    -   d. Chemical functionality can further extend the performance of        the insulation polymer.

Examples of such additives disclosed include:

Antioxidants such as hindered phenolic additives based on2,6-di-tert-butyl phenol derived products. In addition to their functionduring the extrusion process, they also slow the growth of water trees.An example of antioxidants that are used include Irgastab Cable KV10(4,6-bis (octylthiomethyl)-o-cresol), a sulfur containing product (CAS#110553-27-0) from BASF.

Metallocenes wherein a metallic atom such as Fe, Mn, Ni, Co, Ru or Os is“sandwiched” between two cyclopentadienyl rings. Specific examplesinclude ferrocene and derivatives thereof, such as n-butylferrocene andoctanoyl ferrocene. Such components act as voltage stabilizers and UVabsorbers.

Voltage stabilizers, such as 1,3-diketones (e.g., avobenzone), esters ofacetoacetic acid (e.g., the ethyl ester or n-propyl ester; see GermanPatent No. 3017442, Mar. 8, 1983), or geranyl acetone (CAS #689-67-8).

Hindered Amine Light Stabilizers (HALS), represented by such commercialproducts as TINUVIN®123 (CAS #129757-67-1) and TINUVIN®152 (CAS#191743-75-6) from BASF, and Sanduvor 3058 (CAS #79720-19-7) from Cytec.Such materials are well known in the art to scavenge free radicals andmitigate the damage caused by UV emissions within polymers. Additionalexamples of HALS may be found in, e.g., U.S. Pat. No. 5,719,218, herebyincorporated by reference.

UV absorbers and energy quenchers, including benzotriazoles and nickelchelates, such as those listed in U.S. Pat. No. 4,870,121, herebyincorporated by reference. Specific examples include TINUVIN®1130(mixture of CAS #104810-47-1 and CAS #104810-48-2 and polyethyleneglycol) and TINUVIN® 479 (CAS #204848-45-3) from BASF. UV absorbingmaterial, such as octocrylene and menthylanthranilatementhylanthranilatementhylanthranilate, benzophenone (available under the tradename Uvinul@3008 from BASF), substituted benzophenones and TINUVIN®400(CAS #153519-44).

When a rejuvenation fluid, containing additives such as those describedabove, is utilized, it is highly desirable that the various protectivecomponents diffuse rapidly into the cable insulation to prevent furtherdegradation or failure. At the same time, it is expected that thecomponents of the rejuvenation fluid will prolong the useful life of thecable for literally decades. Conventional additives are discretemolecules or polymers whose natures do not change over time.Consequently, their diffusion rates also do not change over time. Aconventional additive molecule which has a rapid diffusion rate thatallows it to provide protection for the cable insulation shortly afterinjection of the rejuvenation fluid will not provide adequate long termprotection because it will diffuse through the cable wall and be lost tothe exterior. In contrast, a conventional additive which has a slowdiffusion rate that allows it to provide long term protection will takemonths or years to reach an effective level in the cable insulation,risking cable failure in the interim.

The current state of the art compositions, utilizing the abovefunctional additives suffer from either a significant lag time before aneffective level is reached or a lack of permanence.

This is illustrated by two commercial antioxidants,2,6-Di-tert-butylphenol (Ethanox 701) and 4,6-bis(octylthiomethyl)-o-cresol (IRGASTAB Cable KV-10). FIG. 1 illustratesthe exudation of the two materials from polyethylene model cables. Theprocedural details for exudation experiments are given later.2,6-Di-tert-butylphenol rapidly diffuses through the polyethylene walland into the water in which the model cables are soaking. Over 95% ofthe material is lost in less than 4000 h at 55° C. In contrast, KV-10diffuses much more slowly, and over 35% is still contained in thepolyethylene after 40,000 h at 55° C. The faster diffusing2,6-Di-tert-butylphenol would not provide comparable long-termantioxidant protection compared to KV-10 in an underground electricalcable.

FIG. 2 illustrates the permeation of the two materials into disks ofpolyethylene at 55° C. Procedural details of the permeation experimentsare given later. More rapidly diffusing 2,6-Di-tert-butylphenol reachessaturation (12.9 wt %) in about 145 h, and it is at 90% of saturation in73 h. In contrast, KV-10 which is slower diffusing and much less soluble(takes 193 h to reach saturation (3.3 wt %) and 116 h to reach 90% ofsaturation. The difference in time to reach 90% saturation at 55° C.could be equivalent to weeks or months of difference at normalunderground cable temperatures, so the less rapidly diffusing KV-10would not provide short term protection to a cable treated with it.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the following drawings.

FIG. 1 is an illustration of the exudation of the two prior artmaterials from model cable.

FIG. 2 is an illustration of the permeation of the two prior artmaterials into disks of polyethylene at 55° C.

FIG. 3 is a graph displaying the average overall retention for the sevenmaterials.

FIG. 4 is a graph of the PE retention measured for each model cable ofTable 1.

FIG. 5 is a graph showing the results of Experiment 1A.

FIG. 6 is schematic view of a high-voltage high-frequency amplifiercontrol.

FIG. 7 is a Weibull plot illustrating AC-breakdown performance of 3treatment groups.

FIG. 8 is a whisker plot showing AC-breakdown performance for the testgroups.

FIG. 9 is a graph displaying the permeation of four materials.

FIG. 10 is a whisker plot showing the weight gain versus gelformulation.

FIG. 11 is a graph displaying the viscosity versus gel time for 3inhibitors.

DETAILED DESCRIPTION OF THE INVENTION

Described herein are novel silane functional additives specifically foruse with underground cable insulation rejuvenation fluids and gels toenhance and extend long term performance of underground cableinsulation. By covalently binding to the oligomer formed upon hydrolysisof rejuvenation fluid or forming oligomers among themselves uponhydrolysis, these additives provide greater long-term stability by beingimmobilized in the matrix.

Tree-Retardant Fluid Embodiment

The instant method relates to a method for extending the useful life ofat least one in-service electrical cable section having a strandedconductor surrounded by a conductor shield encased in a polymericinsulation jacket with an outer insulation shield, and having aninterstitial void volume in the region of the conductor, with the cablesection having an average operating temperature T.

One embodiment of the method comprises: injecting a dielectricenhancement fluid composition into the interstitial void volume, and/orinto the space between the insulation jacket and outer insulationshield, said composition comprising at least one component selectedfrom:

-   -   (1) a water-reactive material selected from:        -   (i) a class 1 organosilane monomer, as described herein,            having at least two water-reactive groups;        -   (ii) the above organosilane monomer (i) wherein at least one            of the water-reactive groups has been substituted with a            condensable silanol group;        -   (iii) an oligomer of the above organosilane monomer (i); or        -   (iv) a co-oligomer of the above organosilane monomer (i)            with a different organosilane monomer, said organosilane            monomer (i) having a diffusion coefficient at least about 15            times greater than the diffusion coefficient of its            corresponding tetramer, the diffusion coefficient being            determined at temperature T.    -   (2) a water-reactive material selected from:        -   (i) a class 2 organosilane monomer, as described herein,            having at least two water-reactive groups;        -   (ii) the above organosilane monomer (i) wherein at least one            of the water-reactive groups has been substituted with a            condensable silanol group; or        -   (iii) an oligomer of the above organosilane monomer (i);    -   (3) a non-water-reactive organic material which has a diffusion        coefficient of less than about 10⁻⁹ cm²/sec and an equilibrium        concentration of at least about 0.005 gm/cm³ in said polymeric        insulation, the diffusion coefficient and the equilibrium        concentration being determined at temperature T; or    -   (4) an organic compound having an equilibrium concentration in        the polymeric insulation at 55° C. which is less than 2.25 times        the equilibrium concentration at 22° C.;    -   (5) silane functional additives derived from:        -   (i) antioxidants such as hindered phenolic additives based            on 2,6-di-tert-butyl phenol derived products.        -   (ii) voltage stabilizers based on metallocenes wherein a            metallic atom such as Fe, Mn, Ni, Co, Ru or Os is            “sandwiched” between two cyclopentadienyl rings.        -   (iii) free radical scavengers that mitigate the damage            caused by UV emissions within polymers such as Hindered            Amine Light Stabilizers, based on tetramethyl piperidine            derivatives.        -   (iv) UV absorbers and energy quenchers, including            benzotriazoles, triazines, benzophenones, nickel chelates;            and/or    -   (6) at least one material which functions as a catalyst for the        hydrolysis and condensation of the water reactive materials of        (1), (2), and (5), including but not limited to strong acids and        certain compounds of titanium and tin.

Further, the instant method uses a computer simulation method todetermine a flux-weighted temperature of a cable section experiencing afluctuating load, defined infra, which may be used to assess diffusionand solubility of components being used to treat the cable, the lattercalculated temperature resulting in better prediction of ultimate cableperformance than the above recited average operating temperature T.

The above method may also be practiced by injecting the fluid into theinterstitial void volume of a cable and confining it therein at anelevated pressure.

The first component class (Class 1) according to the present method isselected from: a water-reactive organosilane monomer having at least twowater-reactive groups (i.e., the organosilane can undergo hydrolysis andsubsequent condensation), such an organosilane monomer wherein at leastone of the water-reactive groups has been substituted with a condensablesilanol group (i.e., it has been partially or completely hydrolyzed), anoligomer of the above described monomers, or a co-oligomer of the abovemonomers with a non-Class 1 organosilane, each oligomer or co-oligomerhaving either residual water-reactive and/or silanol functionality.Thus, for example, the organosilane can be an alkoxy-functionalorganosilane, a reaction product thereof which contains residual alkoxy,or an enoloxy-functional organosilane, such as those illustrated below.Additional water-reactive systems contemplated include ketoximino,amino, amido, acyloxy and hydrido groups bonded to silicon. For thepurposes herein, the monomer (or the monomer parent of anyabove-mentioned oligomer or co-oligomer) of the Class 1 componentexhibits a diffusion coefficient in the insulation polymer which is atleast about 15 times greater than that of the corresponding tetramer,the latter being terminated with either the residual water-reactivegroup(s) or silanol group(s). This ratio of diffusion coefficients ofmonomer to tetramer is measured at the average operating temperature ofthe cable, or preferably at the above defined flux-weighted temperatureand is preferably greater than about 20.

Examples of Class 1 Component include:

-   phenylmethyldimethoxysilane-   (3-methylphenyl)methyldimethoxysilane-   3-cyanopropylmethyl dimethoxysilane-   di(p-tolyl)dimethoxysilane-   (4-methylphenyl)methyldimethoxysilane-   3-cyanobutylmethyldimethoxysilane-   (4-methyphenethyl) methyldimethoxysilane-   dimethyldi-n-butoxysilane

When a Class 1 component is included in a dielectric enhancement fluidwhich also contains another condensable silane (i.e., not a Class 1component but one which can condense with a Class 1 component), aco-oligomer can form between these species upon hydrolysis/condensationin addition to the respective homo-oligomers. Thus, since some unitscontain the larger and/or less flexible Class 1 group, the mass flux ofthe total oligomer is retarded. Put another way, judicious formulationwith Class 1 components allows the tailoring of the total oligomerexudation flux to a value lower than for the alkoxysilanes used in theprior art cable restoration methods. Preferred Class 1 componentsinclude p-tolylethylmethyl-dimethoxysilane,cyanopropylmethyldimethoxysilanes (e.g.,3-cyanopropylmethyl-dimethoxysilane), andcyanobutylmethyldimethoxysilanes (e.g.,3-cyanobutylmethyl-dimethoxysilane). It is also preferred that theorganoalkoxysilane components of any class described herein are used inconjunction with a condensation catalyst.

The second component class (Class 2) comprises water reactiveorganosilane monomers, condensable monomers, oligomers or co-oligomerssimilar to those described above which contain at least one group orsidechain (—R) attached to silicon having between 7 and about 20saturated carbon atoms. This R group can have a linear, branched, orcyclic structure and can further comprise heteroatoms such as oxygen,nitrogen, and sulfur provided it also comprises at least 7 (—CH₂—)units, the latter not necessarily, but preferably, being sequential.Furthermore, R can be a substituted group if it meets the abovecriterion. Thus, for example, this group can have a skeleton such asCH₃—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—, CH₃—CH₂—CH₂—O—CH₂—CH₂—CH₂—CH₂—CH₂—,Ph-CH₂—CH₂—CH₂—CH₂—CH₂—N—CH₂—CH₂—, Hex-CH₂—CH₂—CH₂—CH₂—CH₂—O—CH₂—CH₂—,Hex-CH₂—CH₂—, CH₂═CH—CH₂—CH₂—CH₂—CH₂—CH₂—CH—CH₂—, and so on, wherein Phand Hex represent phenyl group and cyclohexyl group, respectively.

Preferably, Class 2 comprises C₇ to C₂₀ alkyl-functional alkoxysilanes,such as:

-   Phenyloctyldialkoxysilane-   Dodecylmethyldialkoxysilane-   n-octadecyldimethylmethoxysilane-   n-decyltriethoxysilane-   dodecylmethyldiethoxysilane-   dodecyltriethoxysilane-   hexadecyltrimethoxysilane-   1-docosenyltriethoxysilane-   n-octyltrimethoxysilane-   n-octadecyltrimethoxysilane-   and partial hydrolyzates of the above alkoxysilanes

The larger hydrocarbon groups will generally increase the equilibriumconcentration of the Class 2 component as well as decrease itsdiffusivity in the insulation polymer. Furthermore, while someunsaturation on the side chains is permitted, these R groups arepreferably saturated straight chain hydrocarbons, such as octyl, nonyl,decyl, undecyl, dodecyl, tetradecyl and hexadecyl. Less preferred arearylalkyl or substituted alkyl side chains provided the above criterionis met. It is believed that increasing the number of methylene units ofthe hydrocarbon group of the Class 2 component also retards diffusiondue to steric hindrance. Although a perceived disadvantage of employingtoo many methylene units is that their bulk fills the limited treatmentvolume available, it is believed that the above recited chain lengthswill provide the benefits of increased longevity without undulysacrificing excess interstitial volume and without requiring too long atime for the material to diffuse into the cable insulation. Thesediffusion requirements vary, as described previously, depending on theexpected operating temperature profile of the cable. As indicated inconnection with the description of the Class 1 component, a co-oligomerwould form when a Class 2 component is combined with anotheralkoxysilane to form the dielectric enhancement fluid, which co-oligomerwould contain the relatively soluble hydrocarbon segment. While priorart alkoxysilane dielectric enhancement fluids such asphenylmethyldimethoxysilane trade off a large decrease in solubility toattain the desired decrease in diffusivity with increasing degree ofpolymerization, Class 2 materials enjoy a less severe decrease inequilibrium concentration as the degree of polymerization of the Class 2component increases. Likewise, Class 2 components enjoy a lowerreduction in equilibrium concentration (i.e., solubility in theinsulation polymer) when employed in mixtures with other condensablematerials as they co-oligomerize versus prior art alkoxysilanedielectric enhancement fluids, thereby mitigating the chemicalcondensation contribution to the supersaturation phenomenon described inU.S. Pat. No. 6,162,491. To illustrate this point, consider apolyethylene insulation jacket which is saturated with acatalyst-containing organoalkoxysilane monomer such asphenylmethyldimethoxysilane and is exposed to moisture. As the monomerhydrolyzes and condenses to form, e.g., a dimer, it immediately tends tosupersaturate the polyethylene since this dimer has a lower solubilitythan one of the instant Class 2 materials. It should be appreciated thatneither a Class 1 component nor a Class 2 component has to diffusethrough the insulation polymer as rapidly as the oligomer of any otheralkoxysilane present in the dielectric enhancement fluid with which itis to co-oligomerize. For example, if the other alkoxysilane werephenylmethyldimethoxysilane, this fluid could permeate into theinsulation wherein a portion would dimerize (assuming water and anappropriate catalyst is also present). As long as some of the Class 1 orClass 2 component (i.e., the monomer thereof) can “catch up” with thedimer and higher oligomers of the phenylmethyldimethoxysilane, it willhave an opportunity to co-oligomerize therewith, thereby creating ahetero-trimer or higher hetero-oligomer. Thus, while many of the Class 1or 2 materials have lower diffusion rates than, e.g.,phenylmethyldimethoxysilane, they would generally have higher diffusionrates than the tetramer, and preferably the dimer, of the lattercompound.

The third component class (Class 3) comprises non-water-reactivematerials which have a diffusion coefficient of less than about 10⁻⁹cm²/sec and have an equilibrium concentration of at least about 0.005gm/cm³ in the insulation polymer of the cable at the average operatingtemperature of the cable T or, preferably, at above definedflux-weighted temperature T_(flux-avg). According to the instant method,the amount of Class 3 component is limited by the above described oversaturation phenomenon and the amount supplied to a cable is controlledby proper formulation of the total dielectric enhancement fluidcomposition as well as the total quantity thereof that is injected.Thus, it is contemplated that the higher the equilibrium concentration,the better. It is further preferred that the equilibrium concentrationof this component is at least 0.01 gm/cm³ in the insulation polymer atthe average operating temperature of the cable or, preferably, at abovedefined flux-weighted temperature.

Non-limiting examples of the Class 3 components include:

-   -   1. Metallocenes wherein a metallic atom such as Fe, Mn, Ni, Co,        Ru or Os is “sandwiched” between two cyclopentadienyl rings.        Specific examples include ferrocene and derivatives thereof,        such as n-butylferrocene and octanoyl ferrocene. Such components        act as voltage stabilizers and UV absorbers.    -   2. Hindered Amine Light Stabilizers (HALS), represented by such        commercial products as TINUVIN®123 (CAS #129757-67-1) and        TINUVIN®152 (CAS #191743-75-6) form Ciba® and Sanduvor 3058 (CAS        #79720-19-7) from Cytec. Such materials are well known in the        art to scavenge free radicals and mitigate the damage caused by        UV emissions within polymers. Additional examples of HALS may be        found in, e.g., U.S. Pat. No. 5,719,218, hereby incorporated by        reference.    -   3. Other light stabilizers, including triazoles and nickel        chelates, such as those listed in U.S. Pat. No. 4,870,121,        hereby incorporated by reference. Specific examples include        TINUVIN®1130 (mixture of CAS #104810-47-1 and CAS #104810-48-2        and polyethylene glycol) and TINUVIN® 479 (CAS #204848-45-3)        from Ciba.    -   4. UV absorbing material, such as octocrylene and        menthylanthranilate, benzophenone (available under the trade        name Uvinul®3008 from BASF), substituted benzophenones and        TINUVIN0400 (CAS #153519-44-9).    -   5. Hydrolyzates of Class 1 or Class 2 components previously        listed which meet the solubility and diffusivity criteria for        class 3 components.

Those skilled in the art will readily recognize that many of the Class 3components are solids at typical injection temperatures and, therefore,can be injected only as part of a dielectric enhancement formulationwherein the solid is either dissolved or suspended in a fluid. Ofcourse, this restriction applies to any solid component according to thepresent method (e.g., ferrocene). An advantage of employing such a solidcomponent is that it imparts an increased density to the injectionformulation, which allows even more functional material to be suppliedto the cable insulation.

The fourth component class (Class 4) comprises materials which have aratio of equilibrium concentration (solubility) at 55° C. to equilibriumconcentration at 22° C. in the cable insulation polymer of less than2.25, and more preferably less than 2.0. Prior art materials (first tworows) suffer from values more than 2.25; this increases the risk ofsupersaturation when a cable goes through significant temperaturefluctuations, as described by U.S. Pat. No. 6,162,491. Class 4 materialsexhibit a surprisingly low change in equilibrium concentration in theinsulation polymer as a function of temperature, thereby decreasingtheir contribution to the above cited supersaturation phenomenon. It isnoted that ferrocene is representative of both class 3 and class 4components and that cyanopropyl methyldimethoxysilanes and cyanobutylmethyldimethoxysilanes are representative of both class 1 and class 4components. Non-limiting examples of Class 4 materials are ferrocene(this is both a class 3 and class 4 component),3-cyanobutylmethyldimethoxysilane, 3-cyanopropylmethyldimethoxysilaneand 2-cyano-butylmethyldimethoxysilane.

An additional advantage associated with the use of the above fourdescribed component classes is that the components according to theinstant method generally exhibit relatively low vapor pressures and highflash points which decrease the fire and explosion hazard associatedwith injection of volatile materials.

The fifth component class comprises silane functional variants of class3 components, including:

-   -   (i) Antioxidants such as hindered phenolic additives based on        2,6-di-tert-butyl phenol derived products.    -   (ii) Voltage stabilizers based on metallocenes wherein a        metallic atom such as Fe, Mn, Ni, Co, Ru or Os is “sandwiched”        between two cyclopentadienyl rings.    -   (iii) Free radical scavengers that mitigate the damage caused by        UV emissions within polymers such as Hindered Amine Light        Stabilizers, based on tetramethyl piperidine derivatives.    -   (iv) UV absorbers and energy quenchers, including        benzotriazoles, triazines, benzophenones, nickel chelates.

The sixth component class comprises one or more hydrolysis/condensationcatalysts. The catalysts contemplated herein are any of those known topromote the hydrolysis and condensation of organoalkoxysilanes.Typically, these are selected from organometallic compounds of tin,manganese, iron, cobalt, nickel, lead, titanium or zirconium. Examplesof such catalysts include alkyl titanates, acyl titanates and thecorresponding zirconates. Specific non-limiting examples of suitablecatalysts include tetra-t-butyl titanate (TBT), dibutyltindiacetate(DBTDA), dibutyltindilaurate (DBTDL), dibutyltindioleate,tetraethylorthotitanate, tetraisopropyl titanate (TIPT),tetraoctadecylorthotitanate, dibutyltindioctoate, stannous octoate,dimethyltinneodeconoate, di-N-octyltin-S, S-isooctylmercaptoacetate,dibutyltin-S, S-dimethylmercaptoacetate, ordiethyltin-S,S-dibutylmercaptoacetate. In general, the catalyst is addedat a level of about 0.05 to about 5% based on the total weight of theorganoalkoxysilane components. More typically, it is supplied at a levelof about 0.1 to about 2% or at a level of about 0.2 to 1% by weightaccording to the above-mentioned basis.

Also preferred are condensation catalysts based on an acid having a pKaless than about 2.1 which have been well documented in U.S. Pat. No.7,700,871. The acid catalyst to be included in the dielectricproperty-enhancing fluid composition of the instant method has a pKaless than about 2.1 and is added in an effective amount for promotingthe hydrolysis reaction of the organoalkoxysilane with water andsubsequent condensation of the resulting product of hydrolysis. For thepurposes herein, pKa has its usual definition of the negative logarithm(base 10) of the equilibrium constant (Ka) for the dissociation of theacid. Preferably, the acid to be used in the instant method has a pKavalue between about −14 and about 0. The optimum acid catalyst contentmay be determined experimentally using, e.g., the below described modelcable tests. One skilled in the art will appreciate that it is desirableto employ an amount of acid catalyst which results in the retention ofessentially all hydrolysis/condensation products in the model cable.However, this amount should be balanced by the cost of the catalyst.Moreover, the acid content should be kept as low as possible since itcan contribute to the corrosion of the cable conductor, and this factorshould be considered in the balance. Although it is recognized that thecatalyst and the organoalkoxysilane interact on a molar basis, the acidcatalyst (b) should generally be added at a level of about 0.02 to about1% based on the weight of the organoalkoxysilane (a) component. Moretypically, it should be supplied at a level of from about 0.05 wt. % toabout 0.6 wt. %, preferably from about 0.06 wt. % to about 0.5 wt. %.Preferably, the acid catalyst (b) is selected from strong acids whichessentially dissociate completely in an aqueous solution. For thepurposes herein, preferred acids include dodecylbenzenesulfonic acid(DDBSA), methanesulfonic acid, trifluoromethanesulfonic acid,benzenesulfonic acid, alkyl substituted benzenesulfonic acids and alkylsubstituted naphthalene sufonic acids, sulfuric acid, nitric acid,trifluoracetic acid, dichloroacetic acid and phosphoric acid.

Furthermore, these components may be included in a dielectricproperty-enhancing fluid composition to be used either in a conventional(low-pressure) restoration method or the previously mentionedhigh-pressure treatment method of U.S. Pat. No. 8,572,842 which employsspecial high-pressure connectors of the type described in U.S. Pat. No.7,683,260. In brief, the high-pressure method comprises filling theinterstitial void volume of the cable with at least one dielectricproperty-enhancing fluid composition at a pressure below the elasticlimit of the polymeric insulation jacket, and confining the dielectricproperty-enhancing fluid within the interstitial void volume at aresidual pressure greater than about 50 psig, the pressure being imposedalong the entire length of the cable and being below the elastic limit,wherein the composition includes at least one component selected fromClass 1, Class 2, Class 3 or Class 4. As used herein, the term “elasticlimit” of the insulation jacket of a cable section is defined as theinternal pressure in the interstitial void volume at which the outsidediameter (OD) of the insulation jacket takes on a permanent set at 25°C. greater than 2% (i.e., the OD increases by a factor of 1.02 times itsoriginal value), excluding any expansion (swell) due to fluid dissolvedin the cable components. This limit can, for example, be experimentallydetermined by pressurizing a sample of the cable section with a fluidhaving a solubility of less than 0.1% by weight in the conductor shieldand in the insulation jacket (e.g., water), for a period of about 24hours, after first removing any covering such as insulation shield andwire wrap. After the pressure is released, the final OD is compared withthe initial OD in making the above determination. The actual pressureused to fill the interstitial void volume is not critical provided theabove-defined elastic limit is not attained. After the desired amount ofthe fluid has been introduced, the fluid is confined within theinterstitial void volume at a sustained residual pressure greater thanabout 50 psig. It is preferred that the residual pressure is betweenabout 100 psig and about 1000 psig, most preferably between about 300psig and 600 psig. Further, it is preferred that the injection pressureis at least as high as the residual pressure to provide an efficientfill of the cable section (e.g., 550 psig injection and 500 psigresidual). In another embodiment of this method, the residual pressureis sufficient to expand the interstitial void volume along the entirelength of the cable section by at least 5%, again staying below theelastic limit of the polymeric insulation jacket. It is alsocontemplated that the dielectric property-enhancing fluid compositionmay be supplied at a pressure greater than about 50 psig for more thanabout 2 hours before being contained in the interstitial void volume. Itis further preferred that the dielectric property-enhancing fluidcomposition is selected such that the residual pressure decays toessentially zero psig due to diffusion into the conductor shield andinto the insulation jacket of the cable. This pressure decay generallyoccurs over a period of greater than about 2 hours, preferably in morethan about 24 hours, and in most instances within about two years ofcontaining the fluid composition. It is to be understood that thispressure decay results from diffusion of the various components of thecomposition out of the interstitial volume and not by leaking past anyconnector.

The method for treating cables under sustained pressure to enhance thecable segment involves filling the interstitial void volume with atleast one dielectric property-enhancing fluid at a pressure below theelastic limit of the polymeric insulation jacket, and subsequentlyconfining the dielectric property-enhancing fluid within theinterstitial void volume at a desirable sustained residual pressureimposed along the entire length of the cable segment and, again, belowthe elastic limit. The method for treating cables under sustainedpressure exploits the discovery that, when the interstitial void volumeof a cable segment is filled with a dielectric property-enhancing fluidand the fluid confined therein at a high residual pressure, the volumeof fluid actually introduced significantly exceeds the volume predictedfrom a rigorous calculation of the cable's expansion at the imposedpressure. The difference between the observed and calculated volumechange increases with pressure and is believed to be due mainly to theaccelerated adsorption of the fluid in the conductor shield as well astransport thereof through the conductor shield and insulation of thecable. Thus, with sufficient residual sustained pressure, it is possibleto expand the insulation jacket of an in-service cable segment in amanner that is so slight as to not cause any mechanical damage to thecable or to induce any untoward electrical effects, yet large enough tosignificantly increase the volume of dielectric property-enhancing fluidwhich can be introduced. As a result, and unlike the prior art, theintegrated method does not require the soak period, and the associatedexternal pressure reservoir, to introduce a sufficient amount of fluidto effectively treat the cable segment. As noted elsewhere herein, theterm “elastic limit” of the insulation jacket of a cable segment isdefined as the internal pressure in the interstitial void volume atwhich the outside diameter of the insulation jacket takes on a permanentset greater than 2% at 25° C. (i.e., the OD increases by a factor of1.02 times its original value), excluding any expansion (swell) due tofluid dissolved in the cable components. For the purposes herein, it ispreferred that the above-mentioned residual pressure is no more thanabout 80% of the above defined elastic limit.

The in-service cable segment to which the methods discussed aregenerally applied is the type used in underground residentialdistribution and typically comprises a central core of a stranded copperor aluminum conductor encased in a polymeric insulation jacket. Thestrand geometry of the conductor defines an interstitial void volume. Asis well known in the art, there is usually also a semi-conductingpolymeric conductor shield positioned between the conductor andinsulation jacket. However, this shield can also be of a highpermittivity material sometimes utilized in EPR cables. Further, lowvoltage (secondary) cables do not employ such a shield. In addition, thecables contemplated herein often further comprise a semi-conductinginsulation shield covering the insulation jacket, the latter beingordinarily wrapped with a wire or metal foil grounding strip and,optionally, encased in an outer polymeric, metallic, or combination ofmetallic and polymeric, protective jacket. The insulation material ispreferably a polyolefin polymer, such as high molecular weightpolyethylene (HMWPE), cross-linked polyethylene (XLPE), a filledcopolymer or rubber of ethylene and propylene (EPR), vinyl acetate or isa solid-liquid dielectric such as paper-oil. The base insulation mayhave compounded additives such as anti-oxidants, tree-retardants,plasticizers, and fillers to modify properties of the insulation. Mediumvoltage, low voltage and high voltage cables are contemplated herein. Asnoted elsewhere herein, the term “in-service” refers to a cable segmentwhich has been under electrical load and exposed to the elements for anextended period. In such a cable, the electrical integrity of the cableinsulation has generally deteriorated to some extent due to theformation of water trees, as described above. It is also contemplated,however, that the method discussed can be used to enhance the dielectricproperties of a new cable as well as an in-service cable. For thepurposes herein, “sustained pressure” indicates that the fluid iscontained or trapped within a cable segment's interstitial void volumeat the residual pressure after the pressurized fluid source is removed,whereupon the pressure decays only by subsequent permeation through theconductor shield and insulation, as described infra. The method fortreating cables under sustained pressure teaches the relationshipbetween pressure and the augmented injection volume under sustainedresidual pressure and demonstrates the feasibility of eliminating orreducing the soak phase on cables with small conductors.

Experiment 1—Exudation Test

This test demonstrates the rate of diffusion for silane variants andtheir retention rate in the insulation compared to conventional fluidadditives.

Samples of the additives at about 20 wt % in toluene for the exudationexperiments were prepared as indicated in Table 1 below. About 0.3 wt %DDBSA (dodecylbenzene sulfonic acid) was added as ahydrolysis/condensation catalyst to the three silane-bound additives.The ferrocene sample had to be heated to 55° C. to get all the solid todissolve in toluene. During injection of this solution into model cable,a little of the ferrocene crystallized out. The silane-BZT is a solid atroom temperature, so it was melted in a 55° C. oven before samplepreparation. All other samples were prepared at room temperature. Exceptfor the ferrocene solution, all the other samples remained homogeneousindefinitely at room temperature.

TABLE 1 Toluene Additive DDBSA Total Additive Weight (g) Weight (g)Weight % Weight (g) Weight % Weight (g) Ferrocene 5.3387 1.3350 20.000.0000 0.000 6.6737 Tinuvin 1130 4.0118 1.0029 20.00 0.0000 0.000 5.0147Tinuvin 123 4.0613 1.0152 20.00 0.0000 0.000 5.0765 HALS-DMS 4.05621.0140 19.92 0.0192 0.377 5.0894 Silane-BZT 7.5473 1.8867 19.94 0.02830.299 9.4623 Silane-AO 4.0004 1.0004 19.94 0.0158 0.315 5.0166 Toluene4.0004 0.0000 0.00 0.0000 0.000 4.0004

Model cable sample are prepared as follows:

Approximately 12″ long pieces of ⅛″ polyethylene tubing are cut from aroll (Freelin Wade 1C-109-10). The tubes are wiped with an acetone-wetpaper towel to remove the ink markings.

An equal number of aluminum wires of approximately 11.5″ length are cutfrom a roll and wiped with an acetone-wet paper towel to remove anygrease and corrosion.

Sufficient numbered metal tags are cleaned with an acetone-wet papertowel and allowed to air dry.

For each sample, the polyethylene tube, the aluminum wire, and the metaltag are separately weighed to 0.1 mg, and the weights are recorded inthe exudation spreadsheet. Liberal use of an anti-static gun and zeroingthe balance after each measurement provide much more repeatable weights.

The aluminum wire is then carefully threaded through the PE tube leavingan approximately equal empty space on each end of the tube. A numberedmetal tag is attached to each sample for identification.

The assembled sample is weighed to 4 decimal places, and the value isrecorded in the exudation spreadsheet. If the difference between thisweight and the sum of the weights of the individual components isgreater than 0.5 mg, the sample should be disassembled and redone.Fluctuating weights are typically due to static electricity or failureto zero the balance.

The fluid to be tested is drawn up into a 1 mL Hamilton Gastight syringefitted with a 16-gauge hypodermic needle. This size of needle fitssnugly into the interior of the polyethylene tubing. Bubbles in thesyringe should be removed before injection of the fluid into the sample.

The syringe is inserted into one end of the tubing, and gentle pressureon the piston is used to push fluid through the tubing until the fluidpasses the far end of the aluminum wire but does not reach the far endof the polyethylene tubing. The needle is then withdrawn from the tube.With low viscosity fluids, care must be taken to keep the two ends ofthe tube level or fluid will flow out the lower end.

The far end of the tube, which is not contaminated with fluid, can besealed by pushing it into a pit on the face of a soldering iron for acount of two and then gently pushing the top and sides of the bead ofsoft polyethylene to form a sealed ball on the end of the tubing. Theend of the tubing through which the needle was inserted must be cleanedbefore sealing. A paper towel is first used to wipe any fluid from theexterior of the tube. Then, for low viscosity fluids, a piece of pipecleaner, available in craft stores, is inserted into the space betweenthe end of the aluminum wire and the end of the polyethylene tube toabsorb fluid. This should be repeated at least once. The end should bewiped again with paper towel and can then be sealed in the manneralready described. For viscous samples, it is usually necessary to cleanthe space between end of the aluminum wire and the end of thepolyethylene tube with a dry pipe cleaner to remove most of thematerial, and then use an acetone-wet pipe cleaner to remove the rest. Aclean pipe cleaner should then be used to make sure no significantresidual acetone remains before sealing.

The sealed model cable sample is weighed to the nearest 0.1 mg, and thevalue is recorded in the exudation spreadsheet.

The set of model cable samples for one fluid is placed into a 16 oz.HDPE jar, the jar is filled with tap water approximating the desiredaging temperature, and the jar is capped. The jar is placed in an ovento maintain the desired test temperature. The time at which the sampleswere placed into the oven is recorded in the exudation spreadsheet.

Samples are measured during the test following procedures below:

-   -   1. The 16 oz. jar is removed from the oven, and the water is        poured out. The samples are placed in a paper towel and wiped to        remove most of the water.    -   2. Each sample and tag combination is then separately wiped with        a fresh paper towel to remove as much of the water as possible.        The tag should be moved on the sample to make sure no water is        left trapped under it.    -   3. Weight of each sample/tag is measured to the nearest 0.1 mg,        and the results are entered into the exudation spreadsheet along        with the time the measurement was made. Both the polyethylene        and the metal of the tag should be in contact with the pan of        the balance and an anti-static gun should be used to avoid        static charge issues.    -   4. The samples are then put back into the 16 oz. HDPE jar, the        jar is filled with tap water approximating the aging        temperature, and the jar is replaced in the oven.

Samples are measured upon completion of exudation by the followingprocedures:

-   -   1. After the exudation curves level off, a final measurement is        made on each sample. This can be done all at one time to get        replicates or staggered over a period to look for ongoing        changes.    -   2. After the sample is dried and weighed as described above, the        seals at each end of the tube are removed and retained, and the        aluminum wire is withdrawn.    -   3. The aluminum wire is wiped clean with an acetone-wet paper        towel and dried by waving it in the air. Its weight is        determined to 0.1 mg, and the weight is recorded in the        exudation spreadsheet. Changes in the weight of the wire can        give indications of corrosion by the test sample.    -   4. The exterior of the model cable is cleaned with an        acetone-wet paper towel. The interior is cleaned by pulling air        through it using a vacuum aspirator to remove as much residual        fluid as possible. Then about 2×30 mL of acetone is pulled        through it, and the sample is dried by pulling air through it        again. The two seals cut off the ends of the sample are wiped        with a paper towel, and their internal cavities are cleaned out        with a pipe cleaner. The combined seals and polyethylene sample        are weighed to the nearest 0.1 mg, and the weight is recorded in        the exudation spreadsheet. The difference between this weight        and the original weight of the polyethylene sample represents        the minimum amount of material retained in the polyethylene.        Since polyethylene is known to lose some weight during heat        aging, the actual weight of retained material is usually        slightly larger.

For the samples shown in Table 1, exudation experiments were conductedusing five samples for each additive. Samples were analyzed forretention in approximately 250-hour increments between 500 and 1500hours.

FIG. 3 is a graph displaying the average overall retention for the sevenmaterials. Since at least 80% of each sample was toluene, weight loss israpid down to about 20% fluid remaining. The pure toluene control samplecontinues to drop to slightly below zero, likely due to the removal of asmall amount of plasticizer. The ferrocene sample continues to declineslowly with time from 20%. The three silane-bound additives, HALS-DMS,Silane-BZT, and Silane-AO, decline rapidly to the upper teens and leveloff there. This decline below 20% is expected due to loss of methanol asthe silane-bound additives are hydrolyzed. Tinuvin 123 rapidly declinesto 20% and levels out there, while Tinuvin 1130 declines to the low 20sand then starts to increase again. This has always been observed duringexudation of Tinuvin 1130 and is ascribed to the polyethylene glycolbackbone, which is hydrophilic, encouraging water to enter and remain inthe cable interstices.

PE retention refers to the material actually retained in thepolyethylene of the sample expressed as weight % of the test material inthe PE. It is calculated by dividing the change in weight of thepolyethylene tube by the original weight of the polyethylene tube. Itvaries widely depending on the material being exuded and aging time. Foreach sample material, one of the five model cables were removed andanalyzed after approximately 500, 750, 1000, 1250, and 1500 hours ofaging time. The PE retention measured for each sample is shown in FIG.4.

All five samples containing only toluene had slightly negative PEretentions, probably due to loss of a small amount of plasticizer.Likewise, Tinuvin 1130 had a slight negative PE retention. This isprobably due to the polar nature of Tinuvin 1130 which severely limitsits solubility in PE.

Silane-AO and Silane-BZT had PE retentions in the range of 0.2-0.3 wt %,and the values were generally constant over the time from 500 to 1500 h.

The values for Tinuvin 123 and HALS-DMS were also fairly constant overthat time period but were at a significantly higher level. The Tinuvin123 gave the highest concentration of the materials tested. Ferrocenewas the only material which did not display a generally constant levelof PE retention. At 500 h, ferrocene had a PE retention of 0.68 wt %,but that steadily declined to only 0.16 wt % for the 1500 h sample. Thisis due to the volatile nature of ferrocene which allows it to exude outof the model cable and be lost to the exterior in a relatively shorttime.

Experiment 1A—Pure Additive Exudation Test

In a similar exudation experiment to that described in Experiment 1,pure additives were injected into miniature cable. As indicated in Table1A below, a small weight percent of DDBSA was added to the Silane-boundadditives to promote the hydrolysis and condensation reactions.

TABLE 1A Weight % Sample Additive DDBSA Total Tinuvin 1130 100.000 0.000100.000 Tinuvin 123 100.000 0.000 100.000 HALS-DMS 99.633 0.377 100.000Silane-BZT 99.701 0.299 100.000 Silane-AO 99.685 0.315 100.000

The results are shown in the graph of FIG. 5 which covers up to 12,000hours of exudation time and can be compared to the results fromExperiment 1 with the toluene dilution.

Similar to Experiment 1, the PE retention for Tinuvin 1130 remainedclose to zero.

Pure Tinuvin 123 level in PE increased from 0.57 wt % at 141 hours toabout 1.53 wt % at 1533 hours. This is slightly higher than the maximumlevel of 1.35 wt % achieved by the 20% Tinuvin 123 sample.

The HALS-DMS solution in toluene gave a virtually constant level of 0.8wt % in PE from 500 hours to 1500 hours, but the pure HALS-DMS variedover the range 1.4 to 1.5 wt % during that time.

In general, the Silane-BZT solution gave a consistent PE level of justover 0.3 wt %, whereas pure Silane-BZT was just over 1.2 wt %.

The Silane-AO solution was just over 0.2 wt % in PE over the time from500 hours to 1500 hours, but pure Silane-AO displayed PE levelsdeclining from 0.7 to 0.6 wt % over the same period.

The dilutions of the Tinuvins gave fairly similar PE concentrations tothe pure materials. In contrast, the dilutions of the silane-boundadditives yielded significantly lower concentrations in PE than the purematerials.

Experiment 2—AC Breakdown Test

This test evaluates the performance of HALS-DMS as a dielectricenhancement fluid against the legacy Tinuvin 123 additive and a controlgroup of untreated cables. Prior to treatment, the samples were agedthrough the application of high-voltage and high frequency to acceleratethe growth of water trees to simulate cable nearing the end of life.Samples were treated with either HALS-DMS or Tinuvin 123 underaccelerated conditions to either 500 or 1,500 hrs. All samples weresubjected to a stepped AC-breakdown test described later to establishinsulation strength. A set of untreated samples will be used toestablish the baseline for comparison.

Model cables where prepared and aged by following the procedure below:

-   -   1. Cut tubing to length of 52″. Record spool identification in        data table.    -   2. Visually inspect tube for defects and remove ink lettering by        lightly rubbing with isopropyl alcohol.    -   3. Soak tubing in 30° C. saltwater (30,000 ppm) for 24 hrs.        Record start time and date.    -   4. Prep tubing by using needle to create 20 water tree sites at        10 mil depth. Water tree sites should be arranged in rows of 5        and 90 degrees apposed over a 2″ test section at exactly        midspan.    -   5. Cut 14-gauge aluminum conductor to an approximate length of        60″.    -   6. Run lubricated conductor through “calibrated” mandrel to        reduce diameter by about 0.010″    -   7. Remove oil by lightly rubbing with alcohol and allow to dry.    -   8. Rub surface of the conductor with HCl for −2 min to increase        surface wetting.    -   9. Rinse the conductor with water.    -   10. Assemble the wetted conductor into tubing using saltwater        (30,000 ppm). Conductor is axially centered in tubing.    -   11. The function generator, digital oscilloscope, and amplifier        are arranged as illustrated in FIG. 6 showing a high-voltage,        high-frequency amplifier control.    -   12. Assemble 6 samples with a ground shield covering the test        section and the conductors tied to the        high-frequency/high-voltage amplifier.    -   13. Place samples in the saltwater bath and adjust saltwater        (30,000 ppm) depth so peak current is 11.5 mA (11.7V/2*4 mA) and        maintain water level throughout test.    -   14. Increase test voltage to 3,600 V (136 V/mil nominal). Record        start date and time.    -   15. Maintain voltage until one sample breaks down (approximately        36 hrs). Record end date and time.    -   16. Remove samples from test and proceed directly to either AC        breakdown step for non-treated samples or to the Injection step        for treated samples.

Samples were injected following the procedures below:

-   -   1. Remove the conductor from each sample assembly used in the        Aging protocol. Rinse the conductor with water, wipe dry and set        aside for the AC Breakdown step.    -   2. Insert a new conductor into each sample to be injected        leaving at least ¼″ empty space at each end. For this step, an        aluminum wire manufactured by Malin Co is used measuring 0.0508″        in diameter. Overall length of new wire should be about 1″        shorter than the tube.    -   3. Draw the injection fluid into a gas-tight syringe through the        needle.    -   4. Insert the needle into one end of the tube and force fluid        through the sample until it reaches the empty space on the other        end. Remove the needle, and heat seal the empty end. Clean fluid        out of the remaining open end using a pipe cleaner. For viscous        fluids, an additional cleaning with an acetone-wet pipe cleaner        may be necessary. The exterior of the sample end should be wiped        with a paper towel to remove fluid. Heat seal the cleaned end.        Record the date and time of injection.    -   5. Put an identification tag on the sealed sample and immerse it        in a 55° C. tap-water bath. Record start date and time. (Note:        buckets should be cleaned and rinsed prior to use).    -   6. Remove the sample from the oven when the accelerated        diffusion is complete (after either 500 or 1,500 hrs). Record        the end date and time.    -   7. Snip the ends of the tube to remove conductor and flush fluid        with shop air. Rinse tubing with acetone and dry with air.    -   8. Proceed immediately to AC breakdown.

Prepare samples for AC breakdown test:

-   -   1. Cut the 14-gauge aluminum conductor to an approximate length        of 60″.    -   2. Run lubricated conductor through “calibrated” mandrel to        reduce diameter by about 0.010″.    -   3. Remove oil by lightly rubbing with alcohol and allow to dry.    -   4. Rub surface of the conductor with HCl for −2 min to increase        surface wetting.    -   5. Rinse the conductor with water.    -   6. Assemble the wetted conductor into tubing using saltwater        (30,000 ppm). Conductor should be axially centered in tubing.    -   7. Place samples in ground braid and install water-style stress        cones.    -   8. Place test sample in saltwater bath (30,000 ppm) so the        terminations are elevated and fill stress cones with de-ionized        water.    -   9. Begin stepped AC breakdown test at 3.1 kV (100V/mil nominal)        and hold for 5 minutes. Record start date and time.    -   10. Increase voltage by 1.2 kV (40V/mil) per step every 5        minutes until breakdown. Record actual time and voltage for each        step.    -   11. When breakdown occurs, record the voltage and the time        duration into step when breakdown occurred.    -   12. Remove the sample from the test setup being careful not to        disturb the breakdown site.    -   13. Within two hours post breakdown, slice through the breakdown        channel using a microtome and record the following:        -   Maximum size of water tree observed (mils)        -   Depth of needle at maximum sized water tree (mils)        -   Actual insulation thickness at breakdown site (mils)

The results of the test are summarized in Table 2 below:

TABLE 2 Nominal Needle Insulation Diffusion Largest Depth @ Thickness @Actual Injection Duration Breakdown Water largest breakdown ACBD BatchSample Fluid (hrs) Voltage (kV) Tree (mils) WT (mils) (mils) (V/mil) 5 ANot Treated — 9.1 24 10 31 293.5 5 B HALS-DMS 500 34.3 26 6 32 1071.9 5C HALS-DMS 1,500 29.3 28 10 32 915.6 5 D Tinuvin 123 500 17.5 27 9 32546.9 5 E Tinuvin 123 1,500 14.0 26 9 31 451.6 6 A Not Treated — 12.6 239 31 406.5 6 B HALS-DMS 500 12.8 25 10 32 400.0 6 C HALS-DMS 1,500 29.528 9 31 951.6 6 D Tinuvin 123 500 11.7 27 9 32 365.6 6 E Tinuvin 1231,500 21.2 29 9 31 683.9 7 A Not Treated — 8.0 24 9 31 258.1 7 BHALS-DMS 500 28.4 29 7 31 916.1 7 C HALS-DMS 1,500 28.3 28 9 31 912.9 7D Tinuvin 123 500 8.9 27 10 31 287.1 7 E Tinuvin 123 1,500 15.3 28 8 32478.1 8 A Not Treated — 11.7 24 9 31 377.4 8 B HALS-DMS 500 27.1 30 1032 846.9 8 C HALS-DMS 1,500 24.8 23 8 32 775.0 8 D Tinuvin 123 500 22.125 9 32 690.6 8 E Tinuvin 123 1,500 13.8 23 9 32 431.3 9 A Not Treated —8.9 21 9 32 278.1 9 B HALS-DMS 500 33.2 23 10 32 1037.5 9 C HALS-DMS1,500 33.2 28 9 32 1037.5 9 D Tinuvin 123 500 21.2 23 9 32 662.5 9 ETinuvin 123 1,500 18.9 25 9 32 590.6 10 A Not Treated — 8.0 23 9 31258.1 10 B HALS-DMS 500 28.5 26 10 31 919.4 10 C HALS-DMS 1,500 28.2 269 31 909.7 10 D Tinuvin 123 500 23.4 24 10 32 731.3 10 E Tinuvin 1231,500 15.2 24 8 31 490.3 11 A Not Treated — 4.3 25 10 31 138.7 11 BHALS-DMS 500 21.2 26 8 32 662.5 11 C HALS-DMS 1,500 32.0 24 9 32 1000.011 D Tinuvin 123 500 18.8 26 8 32 587.5 11 E Tinuvin 123 1,500 8.0 28 831 258.1

The results for 3 cohorts are shown in the Weibull plot of FIG. 7illustrating AC-breakdown performance of 2 treatment cohorts at 500/1500hrs and acontrol cohort.

The AC-breakdown results for the 5 cohorts (the untreated control andtwo injection fluids, each with two treatment durations) are shown inthe whisker plot of FIG. 8.

Experiment 2A—Pure Additive Saturation. Permeation & Diffusivity Test

Permeation experiments with the pure materials were also conductedwherein disks of diameter of 1.6 cm were cut from a 0.25 cm thickpolyethylene sheet. The disks were weighed and then submerged in thepure additives at 55° C. Periodic removal, cleaning, and weighing of thesample provided the data summarized in Table 2A below. Using the timewhen the slab has reached ½ the saturated content of diffusant, thediffusion coefficient can be calculated by D=0.049×thickness²/time.Permeability (P) is the product of the diffusion coefficient (D) andsolubility (S), the diffusion coefficient is calculated by theexpression D=P/S.

Silane-bound additives exhibit significantly higher solubility in thepolyethylene than their Tinuvin counterparts with HALS-DMS reachingalmost 8 wt % in the polyethylene compared to the eventual maximum levelof 2 wt % for Tinuvin 123. Unexpectedly, not only does the HALS-DMSreach a much higher equilibrium solubility in polyethylene than Tinuvin123, it also approaches that equilibrium much more quickly. At 500 hoursof aging at 55° C., Tinuvin 123 has reached only slightly more than halfits eventual equilibrium solubility, but HALS-DMS is over 90% of itsequilibrium value at 500 hours. See graph of FIG. 9.

Because the silane-bound additives hydrolyze and oligomerize inside thepolyethylene, it was hypothesized that they could provide longer termprotection than conventional additives which will eventually diffuse outof the insulation as taught be Vincent in '011 and Bertini and Vincentin '808. Surprisingly, the above data also indicates that they provideeffective protection of the insulation more quickly after injection thantheir non-silane counterparts. This was confirmed by the AC-breakdownexperiment (Experiment 2). Table 2A below gives the equilibriumsaturation levels and the levels at 500 hours aging at 55° C. inpolyethylene for the silane functional additives and for Tinuvin 123 asa reference.

TABLE 2A Saturation Saturation % of Diffusivity @ Level Level at 500 hSaturation 55° C. Additive Wt % @55° C. Wt % @55° C. at 500 h ×10⁻⁸cm²/s Tinuvin 1.78 1.12 63 0.18 123 HALS- 7.69 7.59 99 1.15 DMS AO-DMS4.17 4.14 99 0.79 UV-DMS 3.92 3.80 97 0.92 Ferrocene- 9.67 8.79 91 — DMS

Particular Preferred Aspects of the Invention can be Understood by theFollowing Clauses:

1. Methods for extending the useful life of in-service electrical cable,comprising injecting a dielectric enhancement fluid composition into atleast one section of an electrical cable having a stranded conductorencased in a polymeric insulation jacket, and having an averageoperating temperature T, the composition comprising: (a) at least oneorganosilane (e.g., organoalkoxysilane) functional additive selectedfrom (i) a voltage stabilizer-based alkoxysilane (e.g.,metallocene-based alkoxysilane, (ii) a hindered amine light stabilizer(HALS)-based alkoxylsilane (e.g., tetramethyl piperidine-basedalkoxysilane), and/or (iii) a UV absorber-based alkoxysilane (e.g.,benzotriazole-based, triazine-based, nickel chelate-based); and (b) atleast one catalyst suitable to catalyze hydrolysis and condensation ofthe at least one functional additive of (a), and wherein the injectedcomposition provides for both initial permeation of the at least onefunctional additive into the polymeric insulation, and extendedretention of subsequent condensation products of the at least onefunctional additive in the cable insulation.

2. The method of clause 1, wherein in the methods, the cable section mayhave a stranded conductor surrounded by a conductor shield encased in apolymeric insulation jacket with an outer insulation shield, and mayhave an interstitial void volume in the region of the conductor, andwherein injecting may comprise injecting the dielectric enhancementfluid composition into the interstitial void volume, and/or into thespace between the polymeric insulation jacket and the outer insulationshield.

3. The method of clauses 1 or 2, wherein in the methods, the dielectricenhancement fluid composition may further comprise (c) at least onewater-reactive organosilane material selected from (i) an organosilanemonomer having at least two water-reactive groups, (ii) the organosilanemonomer (i) where at least one of the water-reactive groups issubstituted with a condensable silanol group, (iii) an oligomer of theabove organosilane monomer (i), and/or (iv) a co-oligomer of the aboveorganosilane monomer (i) with a different organosilane monomer, andwherein the catalyst provides for covalent binding of the at least onefunctional additive of (a) to the at least one water-reactive material(c) upon hydrolysis and condensation thereof.

4. The method of clause 3, wherein in the methods, the organosilanemonomer (i) may have a diffusion coefficient at least about 15 timesgreater than the diffusion coefficient of its corresponding tetramer,the diffusion coefficient being determined at the average operatingtemperature T of the at least one section of the in-service electricalcable.

5. The method of any one of clauses 1-4, wherein in the methods, thedielectric enhancement fluid composition may further comprise: (d) anon-water-reactive organic material which has a diffusion coefficient ofless than about 10⁻⁹ cm²/sec and an equilibrium concentration of atleast about 0.005 gm/cm³ in said polymeric insulation, the diffusioncoefficient and the equilibrium concentration being determined at theaverage operating temperature T; and/or (e) an organic compound havingan equilibrium concentration in the polymeric insulation at 55° C. whichis less than 2.25 times the equilibrium concentration at 22° C.

6. The method of any one of clauses 1-6, wherein in the methods, the atleast one water-reactive organosilane material may be anorganoalkoxysilane.

7. The method according to clause 6, wherein in the methods, theorganoalkoxysilanes may be selected from:(3-methylphenyl)methyldimethoxysilane,di(4-methylphenyl)dimethoxysilane, dimethyldi-n-butoxysilane(4-methylphenyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane 3-cyanobutylmethyldimethoxysilane,phenethyltrimethoxysilane, p-tolylethyl)methyldimethoxysilane,(p-styrylethyl)trimethoxysilane, phenylmethyldimethoxysilane,3-(2,4-dinitrophenylamino)propyltriethoxysilane, or3-(triethoxysilylpropyl) p-nitrobenzamide.

8. The method of clause 7, wherein in the methods, theorganoalkoxysilanes may be (p-tolylethyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane, dimethyldi-n-butoxysilane, or3-cyanobutylmethyldimethoxysilane.

9. The method of any one of clauses 1-7, wherein in the methods, theorganoalkoxysilane functional additives may be derived from at least oneof the following stabilizing functionalities; hydroxyphenylbenzotriazole chromophores, hydroxyphenyl triazine chromophores,N-Alkoxy 2,2,6,6-tetramethyl piperidine light stabilizers, and/orferrocene backbones.

10. The method of any one of clauses 1-7, wherein in the methods, thecomposition may further comprise an organoalkoxysilane functionaladditive derived from a hindered phenolic antioxidant backbone.

11. The method of any one of clauses 1-7, wherein in the methods, the atleast one organoalkoxysilane functional additive may have in PEretention of at least 0.2%.

12. The method of any one of clauses 1-7, wherein in the methods, the atleast one organoalkoxysilane functional additive may permeate into thecable insulation reaching at least 90% of saturation in less than 500hours at 55° C.

13. The method of any one of clauses 1-7, wherein in the methods, the atleast one organoalkoxysilane functional additive may have a diffusivityin PE greater than 5.0×10⁻⁹ cm²/s at 55° C. and a PE retention of atleast 0.40 wt % at 5,000 hours at 55° C.

14. The method of clause 9, wherein in the methods, the at least onefunctional additive may be a compound of Formula 1

wherein,m is 1-4;A is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms;X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical;Y is hydrogen, halogen and preferably chlorine, C₁-C₄ acyloxy, C₁-C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁-C₂ alkyloxy;andn is one, two or three.

15. The method of clause 14, wherein the functional additive may be anorganoalkoxysilane compound selected from

16. A method for extending the useful life of in-service electricalcable, comprising injecting a dielectric enhancement fluid compositioninto at least one section of an electrical cable having a strandedconductor encased in a polymeric insulation jacket, and having anaverage operating temperature T, the composition comprising: (a) atleast one functional additive selected from a compound of

wherein,m is 1-4;A is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms;X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical;Y is hydrogen, halogen and preferably chlorine, C₁-C₄ acyloxy, C₁-C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁-C₂ alkyloxy;andn is one, two or three; and

(b) at least one catalyst suitable to catalyze hydrolysis andcondensation of the at least one functional additive of (a), and

wherein the injected composition provides for both initial permeation ofthe at least one functional additive into the polymeric insulation, andextended retention of subsequent condensation products of the at leastone functional additive in the cable insulation.

17. The method of clause 16, wherein in the methods, the functionaladditive may be an organoalkoxysialane compound selected from

18. The method of clause 16 or 17, wherein in the methods, the cablesection may have a stranded conductor surrounded by a conductor shieldencased in a polymeric insulation jacket with an outer insulationshield, and may have an interstitial void volume in the region of theconductor, and wherein injecting may comprise injecting the dielectricenhancement fluid composition into the interstitial void volume, and/orinto the space between the polymeric insulation jacket and the outerinsulation shield.

19. The method of any one of clauses 16-18, wherein in the methods, thedielectric enhancement fluid composition may further comprise (c) atleast one water-reactive organosilane material selected from (i) anorganosilane monomer having at least two water-reactive groups, (ii) theorganosilane monomer (i) where at least one of the water-reactive groupsis substituted with a condensable silanol group, (iii) an oligomer ofthe above organosilane monomer (i), and/or (iv) a co-oligomer of theabove organosilane monomer (i) with a different organosilane monomer,and wherein the catalyst provides for covalent binding of the at leastone functional additive of (a) to the at least one water-reactivematerial (c) upon hydrolysis and condensation thereof.

20. A compound of Formula 1

wherein,m is 1-4;A is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms;X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical;Y is hydrogen, halogen and preferably chlorine, C₁-C₄ acyloxy, C₁-C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁-C₂ alkyloxy;andn is one, two or three.

21. The compound of clause 20, wherein the compound may selected from

Dielectric Gel Embodiment

Another embodiment of the method comprises: injecting a dielectricenhancement gel composition into the interstitial void volume, and/orinto the space between the insulation and outer jacket said compositioncomprising:

-   -   A. an Si—H endblocked polydiorganosiloxane fluid having a        viscosity of 0.5 to about 100 centistokes at 25° C. and        represented by the formula H(R₂SiO)_(x)(R₂Si)H wherein R is        independently selected from alkyl radicals having from 1 to 6        carbon atoms or the phenyl radical and the average value of x is        1 to 40;    -   B. a polydiorganosiloxane fluid having a viscosity of 0.5 to        about 100 centistokes at 25° C. and represented by the formula

-   -   wherein G denotes unsaturated radicals independently selected        from the vinyl group or higher alkenyl radicals represented by        the formula —R′″(CH₂)_(m)CH═=CH₂, in which R′″ denotes        —(CH₂)_(p)— or —(CH₂)_(q)CH═CH—, m is 1, 2 or 3, p is 3 or 6,        and q is 3, 4 or 5, R″ is independently selected from an alkyl        radical having 1 to 6 carbon atoms or a phenyl radical, and y is        on the average from 1 to about 40;    -   C. sufficient hydrosilylation catalyst to cure the mixture        of (A) and (B);    -   D. silane functional variants, including:        -   i. Antioxidants such as hindered phenolic additives based on            2,6-di-tert-butyl phenol derived products.        -   ii. Voltage stabilizers based on metallocenes wherein a            metallic atom such as Fe, Mn, Ni, Co, Ru or Os is            “sandwiched” between two cyclopentadienyl rings.        -   iii. Free radical scavengers that mitigate the damage caused            by UV emissions within polymers such as Hindered Amine Light            Stabilizers, based on tetramethyl piperidine derivatives.        -   iv. UV absorbers and energy quenchers, including            benzotriazoles, triazines, benzophenones, nickel chelates.    -   E. And preferably, at least one material which functions as a        catalyst for the hydrolysis and condensation of the silane        functional variants (D) and does not significantly affect the        cure of the mixture of (A) and (B) by the catalyst (C).

The hydrosilylation catalyst (component C) for the reaction between thepolydiorganosiloxane fluid endblocked with unsaturated organic radicalsand the Si—H endblocked polydiorganosiloxane fluid can include a varietyof hydrosilylation catalysts known to promote the reaction ofvinyl-functional radicals with silicon bonded hydrogen atoms. Activemetal catalysts such as platinum or rhodium-containing metal compoundsare included in this class of catalysts. Platinum catalysts such asplatinum acetylacetonate or chloroplatinic acid are representative ofthese compounds and suitable for use as component C. A preferredcatalyst mixture is a chloroplatinic acid complex ofdivinyl-tetramethyldisiloxane diluted in toluene, commonly known asKarstedt's catalyst.

To the formulation above including parts A, B, C, D, and E, an optionalsiloxane crosslinker selected from short chain linear or cyclicsiloxanes containing SiH functionality or Si-G functionality, in which Ghas the above-defined meaning can be added.

Further, sufficient hydrosilylation inhibitor could be added to theformulation above to extend the time to viscosity doubling or the timeto cure into a non-flowing state. The use of α-acetylenic compounds,especially acetylenic-α,α′-diols as inhibitors for hydrosilylation isdescribed in United States Patent Application Publication No.20140004359A1 and references therein. The use of maleate and fumaratecompounds is well known to those skilled in the art and is described in“The Chemistry of Fumarate and Maleate Inhibitors with PlatinumHydrosilylation Catalysts,” J. Orgmetal. Chem., (1996) 521, 221-227.Examples of suitable fumarate and maleate inhibitors could includedimethylfumarate, diethyfumarate, dibutylfumarate, diphenylfumarate,fumaric acid, dimethylmaleate, diethylmaleate dibutylmaleate,diphenylmaleate, and maleic acid or other such inhibitors.

One or more hydrolysis/condensation catalysts (E) are included in theformulation of A, B, C, and D above. The catalysts contemplated hereinare any of those known to promote the hydrolysis and condensation oforganoalkoxysilanes provided that the hydrolysis/condensation catalystsdo not interfere with the cure of the gel formulation containing (A),(B), (C), optional siloxane crosslinker, and optional hydrosilylationinhibitor.

For example, five gel formulations were prepared, each consisting ofcomponent (A), (CE-4 sold by AB Silicones), component (B), (VS-6 sold byAB Silicones), component (C), (Syl-off 4000 sold by Dow), component (D),(AO-DMS at 2.5 wt %), and optional crosslinker (XL-1340 sold by ABSilicones). Sample 1 with only these components cured in 10 h. TiPT,(titanium(IV) isopropoxide, at 0.3 wt %) was added to Samples 2 and 3which cured in 12.2 h and 11.9 h respectively. Sample 1 contained 17%greater catalyst level, so samples 1, 2, and 3 had essentially the samecure time. In contrast, when DDBSA (dodecylbenzene sulfonic acid) wasadded at a level of 0.3 wt % to Samples 4 and 5, neither had cured after215 h even though Samples 4 and 5 contained four times the catalystlevel of Sample 3.

Therefore, hydrolysis/condensation catalysts of component (E) arepreferred from organometallic compounds of tin, manganese, iron, cobalt,nickel, lead, titanium, or zirconium. Examples of such catalysts includealkyl titanates, acyl titanates and the corresponding zirconates.Specific non-limiting examples of suitable catalysts includetetra-t-butyl titanate (TBT), dibutyltindiacetate (DBTDA),dibutyltindilaurate (DBTDL), dibutyltindioleate,tetraethylorthotitanate, tetraisopropyl titanate (TIPT),tetraoctadecylorthotitanate, dibutyltindioctoate, stannous octoate,dimethyltinneodeconoate, di-N-octyltin-S, S-isooctylmercaptoacetate,dibutyltin-S, S-dimethylmercaptoacetate, ordiethyltin-S,S-dibutylmercaptoacetate. In general, the catalyst is addedat a level of about 0.05 to about 5% based on the total weight of theorganoalkoxysilane components. More typically, it is supplied at a levelof about 0.1 to about 2% or at a level of about 0.2 to 1% by weightaccording to the above-mentioned basis.

Example—Gel Formulation

In one embodiment, a gel formulation could be blended as indicated inTable 3 below:

TABLE 3 Part Manufacturer Component Wt % CAS # A or B AB SpecialtyAndisil VS-6 45.79 68083-19-2 A Silicones AB Specialty Andisil CE-450.01 70900-21-9 A Silicones AB Specialty Andisil XL-1340 0.5569013-23-6 A Silicones Sigma-Aldrich Diethyl maleate 0.08 141-05-9 A ABSpecialty Andisil VS-6 1.20 68083-19-2 B Silicones JohnsonPlatinum(Tetramethyl- 0.06 68478-92-2 B Matthey divinyldisiloxane)Solution in Xylenes Isle Chem HALS-DMS 2.00 2169926-47-8 B Sigma-AldrichTitanium(IV) 0.30 546-68-9 B Isopropoxide

In this embodiment, Part A and Part B are packaged separately and fieldmixed just prior to injection. This process allows the technician tocontrol the start time and ensure injection is completed within theworklife of the gel formulation. However, it is appreciated that othercombinations herein are possible.

Experiment 3—Gel

A gel formulation consisting of vinyl-capped polydimethylsiloxane,hydride-capped polydimethylsiloxane, crosslinker which contained bothterminal and internal Si—H moieties, and diethylmaleate as inhibitor wasprepared and divided into four portions. One portion was kept as acontrol. Silane-bound antioxidant was added at 2.5 wt % to the secondportion, silane-bound HALS was added at 2.5 wt % to the third portion,and both silane-bound HALS and tetraisopropyltitanate (TiPT) were addedat 2.5 and 0.25 wt % respectively to the fourth portion. SufficientSyl-off 4000 catalyst was added to each portion to provide about 10 ppmPt.

For each portion, ten model cables were prepared as described for theexudation test above, and the samples were soaked in tap water atambient temperature. The weights of the model cables were monitored overtime, and periodically, one sample for each portion was evaluated asdescribed in the exudation test to establish the sample retention in PE.The results are summarized in Table 4 below. The gel only samplesaveraged aweight loss of about 0.04% while all samples containingasilane-bound additive saw aweight gain.

TABLE 4 Material % Weight Gain (avg of 7) Gel Only −0.04 Gel +Silane-bound AO +0.07 Gel + Silane-bound HALS +0.08 Gel + Silane-boundHALS + TiPT +0.06

Full results are shown in Table 5 below and FIG. 10 showing percentageweight gain vs. gel formulation.

TABLE 5 Gel Gel + Gel + Gel + HALS- Time (h) Only Time (h) AO-DMS Time(h) HALS-DMS Time (h) DMS + TiPT 125.9 0.02% 126.2 0.18% 52.0 0.03% 48.00.05% 313.0 0.02% 313.2 −0.02% 316.6 0.01% 315.5 0.07% 610.5 0.07% 610.70.04% 610.9 0.13% 719.5 0.05% 1008.7 −0.26% 1008.9 −0.05% 1009.1 −0.04%1006.4 0.05% 2354.5 −0.04% 2354.7 0.15% 2354.9 0.15% 1539.4 0.10% 3072.9−0.01% 3073.2 0.14% 3073.3 0.20% 2186.3 0.14% 4081.5 −0.10% 4081.7 0.04%4081.8 0.05% 2904.7 0.04% 3913.1 0.01%

Experiment 4—Gel Time to Viscosity Doubling

Three batches of Gel Part “A” and Gel Part “B” were prepared accordingto the formulations given in Table 3 with the exception that theinhibitor level was varied. A complete gel sample was made by mixing96.43 parts by weight Part “A” with 3.56 parts by weight Part “B.” Theresulting fluid was drawn into a size 100 Cannon Routine Viscometer, andthe viscometer was immersed in a 35° C. temperature bath. Thetemperature of the viscometer was allowed to equilibrate for 20 min, andthe viscosity of the fluid was measured. Viscosity was measuredperiodically until the observed viscosity was more than double theinitial measurement. This roughly sets the work life duration for thegel formulation and is typically found to be about % of the cure timerequired for the formulation to reach a non-flowable state. Time toviscosity doubling was found to be 8.3 h for the high inhibitorformulation, 6.5 h for the medium inhibitor, and 4.2 h for the lowinhibitor. Time to gel formation was 15.4 h, 11.4 h, and 8.5 h for thehigh, medium, and low inhibitor samples. See FIG. 11 showing a graph forthe viscosity vs. time at 35° C. Similarly, the concentration ofcatalyst could be varied to deliver a specific rate of cure.

Silyl Functional Benzotriazole UV Absorbers

The invention may pertain to benzotriazole compounds of formula (I) or(II) below:

Formulae (I) and (I):

Where:

G₁ and G₆ are independently hydrogen or halogen.

G₂ and G₇ are independently H, cyano, perfluoroalkyl of 1 to 12 carbonatoms, fluoro, chloro, —CO-G₃, −COOG₃, —CONHG₃, —CON(G₃)₂, E₃SO—,E₃SO₂—, —PO(C₆H₅)₂,

O—CO—NH-T₂-Si(OR₂)_(n)(R₁)_(3-n) or —CO—X-T₁-Si(OR₂)_(n)(R₁)_(3-n);

or G₇ is also hydrogen.

or G₂ may also be hydrogen when E₁ is a group of formula (IV) or (V)(see below);

T₁ and T₂ are independently alkylene of 1 to 18 carbon atoms, preferablyalkylene of 2 or 3 carbon atoms, or alkylene-phenylene-alkylene of 8 to20 carbon atoms;

R₁ and R₂ are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of5 to 12 carbon atoms, aryl of 6 to 10 carbon atoms or phenylalkyl of 7to 20 carbon atoms, preferably alkyl of 1 to 6 carbon atoms or phenyl.

n is 1, 2 or 3.

X is —O—, —NE₄- or —NH—.

G₃ is hydrogen, straight or branched chain alkyl of 1 to 24 carbonatoms, straight or branched chain alkenyl of 2 to 18 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms,phenyl, or said phenyl or said phenylalkyl substituted on the phenylring by 1 to 4 alkyl of 1 to 4 carbon atoms;

E₁ is hydrogen, straight or branched chain alkyl of 1 to 24 carbonatoms, straight or branched chain alkenyl of 2 to 24 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms,phenyl, or said phenyl or said phenylalkyl substituted on the phenylring by 1 to 4 alkyl of 1 to 4 carbon atoms or by one or more of thefollowing groups -T₁-Si(OR₂)_(n)(R₁)_(3-n),-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)_(3-n), -T₁-CO—X-T-Si(OR₂)_(n)(R₁)_(3-n),—X-T₁-Si(OR₂)_(n)(R₁)_(3-n), or —X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)_(3-n);

or E₁ is alkyl of 1 to 24 carbon atoms substituted by one or two hydroxygroups.

or E₁ is a group of formula (IV) or (V) (see below).

Formulae (IV) and (V):

Where:

E₂₇ and E₂ are independently alkyl of 1 to 18 carbon atoms, orcycloalkyl of 5 to 12 carbon atoms.

E₂₂, E₂₃, E₂₄, E₂₅ and E₂₆ are independently hydrogen, halogen, straightor branched alkyl of 1 to 18 carbon atoms, alkenyl of 2 to 18 carbonatoms, said alkyl or said alkenyl substituted by one or more halogen,—OCOE₁₁, —OE₄, —NCO, —NHCOE₁₁, or -NE₇E₈, or mixtures thereof, where E₄is straight or branched chain alkyl of 1 to 24 carbon atoms or straightor branched chain alkenyl of 2 to 18 carbon atoms; or said alkyl or saidalkenyl interrupted by one or more —O—, —NH— or -NE₄— groups or mixturesthereof and which can be unsubstituted or substituted by one or more—OH, —OE₄ or —NH₂, or mixtures thereof; or

E₂₂, E₂₃, E₂₄, E₂₅ and E₂₆ are independently phenyl, —OH, —OCOE₁₁,—OE₂₉, —NCO, —NHCOE₁₁, or —NE₇E₈, cyano, nitro, perfluoroalkyl of 1 to12 carbon atoms, —COG₃, —COOG₃, —CON(G₃)₂, —CONHG₃, E₃S—, E₃SO—, E₃SO₂—,—P(O)(C₆H₅)₂, —P(O))OG₃)₂, —SO₂—X₁-E₂₉;

X₁ is —O—, —NH— or -NE₄-.

E₂₉ is straight or branched chain alkyl of 1 to 24 carbon atoms,straight or branched chain alkenyl of 2 to 18 carbon atoms, said alkylor said alkenyl substituted by one or more —OH, —OCOE₁₁, —OE₄, —NCO,—NHCOE₁₁, —NE₇E₈, phthalimido,

or mixtures thereof, where E₄ is straight or branched chain alkyl of 1to 24 carbon atoms or alkenyl of 2 to 18 carbon atoms; or said alkyl orsaid alkenyl interrupted by one or more —O—, —NH— or -NE₄— groups ormixtures thereof and which can be unsubstituted or substituted by one ormore —OH, —OE₄ or —NH₂, or mixtures thereof; or E₂₉ is phenyl orphenylalkyl of 7 to 15 carbon atoms, or said phenyl or said phenylalkylsubstituted by one to three alkyl groups of 1 to 4 carbon atoms;

E₂ and E₉ are independently hydrogen, straight or branched alkyl chainof 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted onthe phenyl ring by one to three alkyl of 1 to 4 carbon atoms or by oneor more of the following groups -T₁-Si(OR₂)_(n)(R₁)_(3-n),-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)_(n), -T₁-CO—X-T₂—Si(OR₂)_(n)(R₁)₃,—X-T₁-Si(OR₂)_(n)(R₁)₃ or —X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R)₃; or E₂ and E₉are independently said alkyl of 1 to 24 carbon atoms or said alkenyl of2 to 18 carbon atoms substituted by one or more —OH, —OCOE₁₁, —OE₄,—NCO, —NH₂, —NHCOE₁₁, —NHE₄ or —N(E₄)₂, or mixtures thereof, where E₄ isstraight or branched chain alkyl of 1 to 24 carbon atoms; or said alkylor said alkenyl interrupted by one or more —O—, —NH— or -NE₄— groups ormixtures thereof and which can be unsubstituted or substituted by one ormore —OH, —OE₄ or —NH₂ groups or mixtures thereof; or

E₁, E₂ and E₉ are also independently -T₁-Si(OR₂)_(n)(R₁)₃—,-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃ or -T₁-CO—X-T₂-Si(OR₂)_(n)(R₁)₃;

E₁₁ is hydrogen, straight or branched chain alkyl of 1 to 18 carbonatoms, straight or branched chain alkenyl of 2 to 18 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, aryl of 6 to 14 carbon atoms orphenylalkyl of 7 to 15 carbon atoms; L is alkylene of 1 to 12 carbonatoms, alkylidene of 2 to 12 carbon atoms, benzylidene, p-xylylene,cycloalkylidene of 5 to 12 carbon atoms orα,α,α′,α′-tetramethyl-m-xylylene.

E₃ is alkyl of 1 to 20 carbon atoms, said alkyl substituted byalkoxycarbonyl of 2 to 9 carbon atoms, hydroxyalkyl of 2 to 20 carbonatoms, alkenyl of 3 to 18 carbon atoms, cycloalkyl of 5 to 12 carbonatoms, phenylalkyl of 7 to 15 carbon atoms, aryl of 6 to 10 carbon atomsor said aryl substituted by one or two alkyl of 1 to 4 carbon atoms or1,1,2,2-tetrahydroperfluoroalkyl where the perfluoroalkyl moiety is of 6to 16 carbon atoms,

E₅ and E₆ are independently the same as E₂; or E₅ and E₈ areindependently hydrogen, —X-E₁, —X—CO-E₂, —X—CO—X₁,—X-T₁-Si(OR₂)_(n)(R₁)_(3-n) or —X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)_(3-n);

X₁ is —NH-E₄ or —X-E₂;

with the proviso that at least one of G₂, G₇, E₁, E₂, E₅, E₈ and E₉contains a group -T₁-Si(OR₂)_(n)(R₁)₃, -T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃,-T₁-CO—X-T₂-Si(OR₂)_(n)(R₁), —X-T₁-Si(OR₂)_(n)(R₁)₃ or—X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)_(3-n); where T₁ and T₂ are independentlyalkylene of 1 to 18 carbon atoms or alkylene-phenylene-alkylene of 8 to20 carbon atoms, and R₁ and R₂ are independently alkyl of 1 to 18 carbonatoms, cycloalkyl of 5 to 12 carbon atoms, aryl of 6 to 10 carbon atomsor phenylalkyl of 7 to 20 carbon atoms, preferably alkyl of 1 to 3carbon atoms or phenyl, and n is 1, 2 or 3.

Preferably, the new benzotriazole is a compound of formula (IA) or(IIA).

Formulae (IA) and (IIA):

Where:

G₁ and G₆ are hydrogen,

G₂ and G₇ are independently H, cyano, CF₃—, fluoro, —CO-G₃, or E₃SO₂—,or G₇ is also hydrogen,

G₃ is straight or branched chain alkyl of 1 to 24 carbon atoms, straightor branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or saidphenyl or said phenylalkyl substituted on the phenyl ring by 1 to 4alkyl of 1 to 4 carbon atoms,

E₁ is phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl orsaid phenylalkyl substituted on the phenyl ring by 1 to 4 alkyl groupsof 1 to 4 carbon atoms each,

E₂ and E₉ are independently straight or branched alkyl chain of 1 to 24carbon atoms, straight or branched chain alkenyl of 2 to 18 carbonatoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbonatoms, phenyl, or said phenyl or said phenylalkyl substituted on thephenyl ring by 1 to 3 alkyl of 1 to 4 carbon atoms; or E₂ is said alkylof 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atomssubstituted by one or more —OH, —OCOE₁₁, —OE₄, —NCO, —NH₂, —NHCOE₁₁,—NHE₄ or —N(E₄)₂, or mixtures thereof, where E₄ is straight or branchedchain alkyl of 1 to 24 carbon atoms; or said alkyl or said alkenylinterrupted by one or more —O—, —NH—, or -NE₄— groups or mixturesthereof and which can be unsubstituted or substituted by one or more—OH, —OE₄, or —NH₂ groups or mixtures thereof;

E₁₁ is hydrogen, straight or branched chain alkyl of 1 to 18 carbonatoms, straight or branched chain alkenyl of 2 to 18 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, aryl of 6 to 14 carbon atoms orphenylalkyl of 7 to 15 carbon atoms.

E₃ is alkyl of 1 to 20 carbon atoms, hydroxyalkyl of 2 to 20 carbonatoms, alkenyl of 3 to 18 carbon atoms, cycloalkyl of 5 to 12 carbonatoms, phenylalkyl of 7 to 15 carbon atoms, aryl of 6 to 10 carbon atomsor said aryl substituted by one or two alkyls of 1 to 4 carbon atoms or1,1,2,2-tetrahydroperfluoroalkyl where the perfluoroalkyl moiety is of 6to 16 carbon atoms;

L is methylene; and

with the proviso that at least one of E₁, E₂ and E₉ contains a group-T₁-Si(OR₂)_(n)(R₁)₃—, -T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃—,-T₁-CO—X-T₂-Si(OR₂)_(n)(R₁), —X-T₁-Si(OR₂)_(n)(R₁)₃— or—X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃-n;

where T₁ and T₂ are independently alkylene of 2 or 3 carbon atoms, andR₁ and R₂ are independently alkyl of 1 to 6 carbon atoms or phenyl, andn is 1, 2, or 3.

Another preferred embodiment of the invention is a compound of formula(IA).

Compound of Formula (IA):

Where:

G₁ is hydrogen,

G₂ is H, CF₃—, fluoro or E₃SO₂—,

E₁ is hydrogen or straight or branched alkyl of 2 to 24 carbon atoms,

E₂ is as defined above, and

E₃ is straight or branched chain alkyl of 1 to 7 carbon atoms,

with the proviso that E₂ contains a group -T₁-Si(OR₂)_(n)(R₁)₃—,-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃—, -T₁-CO—X-T₂-Si(OR₂)_(n)(R₁)₃—,—X-T₁-Si(OR₂)_(n)(R)₃— or —X-T₁-X—CO—X-T₂-Si(OR₂)_(n)(R₁)₃; where T₁ andT₂ are independently alkylene of 2 or 3 carbon atoms, and R₁ and R₂ areindependently alkyl of 1 to 6 carbon atoms or phenyl, and n is 1, 2 or3.

Preferably, the compound of formula (IAIIA) is

-   -   (a) 2-[2-hydroxy-3-(3-triethoxysilyl)        propyl-5-tert-octylphenyl]-2H-benzo-triazole.    -   (b) 2-{2-hydroxy-3-tert-butyl-5-[3-(3-trethyoxysilyl)        propylcarbamoyloxy)-propyl]phenyl}2H-benzotriazole.    -   (c) 2-{2-hydroxy-3-tert-butyl-5-[2-(3-trethyoxysilyl)        propylcarbamoyl-oxy) ethyl]phenyl}-2H-benzotriazole.    -   (d) 2-{2-hydroxy-5-[2-(3-trethyoxysilyl) propyl-carbamoyloxy)        ethyl]-phenyl}-2H-benzotrazole.    -   (e) 2-{2-hydroxy-3-α-cumyl-5-[2-(3-triethyoxysilyl)        propylcarbamoyl-oxy) ethyl]phenyl}-2H-benzotrazole.    -   (f) 2-{2-hydroxy-3-tert-butyl-5-[2-(3-(diethoxymethylsilyl)        propylamino-carbonylethyl]phenyl}-2H-benzotriazole.    -   (g) 2-{2-hydroxy-3-tert-butyl-5-[3-(2-ethoxydimethylsilyl)        ethylcarbonyl-oxy) propyl]phenyl}-2H-benzotriazole.    -   (h) 2-{2-hydroxy-3-tert-butyl-5-[2-(3-ethoxydimethylsilyl)        propyl-oxycarbonyl) ethyl]phenyl}-2H-benzotriazole.    -   (i) 2-[2-hydroxy-3-(ethoxydimethylsilyl)        propyl-5-tert-octylphenyl]-2H-benzotriazole.    -   (j) 5-[3-(diethoxyethylsilyl)        propoxycarbonyl]-2-(2-hydroxy-3-α-cumyl-5-tert-octyl-phenyl)-2H-benzotrazole.    -   (k) 5-[3-(diethoxyethylsilyl)        propylaminocarbonyl]-2-(2-hydroxy-3-α-cumyl-5-tert-octyl-phenyl)-2H-benzotrazole.        -   and the following structures:

Silyl Functional Triazine UV Absorbers

The triazines are novel compounds and have the formula (ViaVlaVia) or(VibVlbVib).

Formulae (VIa) and (VIb):

Where:

p is 0 or an integer from 1-50, r is an integer from 1-50, S₁ and S₃ areeach independently of the other hydrogen, OH, C₁-C₁₂ alkyl orcyclohexyl, S₂ and S₄ are each independently of the other hydrogen, OH,C₁-C₂ alkyl, C₁-C₁₈ alkoxy, halogen or a group —O—IIVIII,

S₅ is a direct bond or a divalent group of one of the followingformulae: —C_(m) H_(2m)—, —(CH₂)_(m)—O—, —(CH₂)_(m)—O—S₆—,—(CH₂)_(m)—CO—X—(CH₂)_(n)—, —(CH₂)_(m)—CO—X—(CH₂)_(n)—O—,

—CH₂—CH(OH)—CH₂—Y—(CH₂)_(m)—, wherein m and n are each independently ofthe other 1-4, S₆ is C₁-C₁₂ alkylene, cyclohexylene or phenylene, S₇ isC₁—C₁₂ alkyl, C₅-C₈ cycloalkyl, phenyl, C₂-C₁₃ alkoxymethyl, C₆-C₉cycloalkoxymethyl or phenoxymethyl, S₈ is a group of formula II, S₉ ishydrogen or methyl, X is —O— or —NS₁₃—, wherein S₁₃ is hydrogen,C₁-C₁₂alkyl, phenyl or a group —(CH₂)₃—I or —(CH₂)₃—O-II, Y is —O— or—NH—, S₁₀, S₁₁ and S₁₂ are each independently of one another C₁-C₁₈alkyl, cyclohexyl, phenyl or C₁-C₁₈ alkoxy, and, if S₂ and S₄ are not agroup —O—II, S₁₀ and/or S₁₁ may also be a group of formula (VIII) below:

Formula (VIII):

S₁₄ is C₁-C₁₂ alkyl, C₅-C₈ cycloalkyl or phenyl, and S₁₅ is hydroxy orC₁-C₄ alkoxy and S₁₆ is hydrogen or C₁-C₄ alkyl or, if r is greater than2, S₁₅ and S₁₆ together may be a direct bond.

One of the substituents S₁, S₂, S₃, S₄, S₇, S₈, and S₁₄ in formula(IaVIaIa) or formula (IbVIbIb) as C₁-C₁₂ alkyl may be a linear orbranched alkyl group. Typical examples of such groups are methyl, ethyl,n-propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, octyl,2-ethylhexyl, nonyl, decyl or dodecyl. S₁₀, S₁₁, and S₁₂ as C₁-C₁₈alkylmay additionally be tetradecyl, hexadecyl or octadecyl.

S₇ and S₁₄ as C₅-C₁₈ cycloalkyl may be cyclopentyl, cyclohexyl orcyclooctyl, preferably cyclohexyl.

S₂, S₄, S₁₀, S₁₁, and S₁₂ as C₁-C₁₈ alkoxy may be linear or branchedalkoxy groups. Exemplary of such groups are methoxy, ethoxy, isopropoxy,butoxy, hexoxy, octyloxy, decyloxy, dodecyloxy or octadecyloxy.

S₁₀, S₁₁, and S₁₂ are preferably C₁-C₄ alkyl or C₁-C₄ alkoxy, and S₁₄ ispreferably C₁-C₄ alkyl.

S₆ as C₁-C₁₂ alkylene may be a linear or branched alkylene group. Suchgroups are typically methylene, dimethylene, 1,2-propylene,trimethylene, 2,2-dimethyltrimethylene, tetramethylene, hexamethylene,octamethylene, or dodecamethylene.

Preferred compounds of formula (VIa) are those wherein S₅ is a directbond or a divalent group of one of the following formulae: —(CH₂)_(m)—,—(CH₂)_(m)—O—, —(CH₂)_(m)—O—R₆—, —(CH₂)_(m)—CO—X—(CH₂)_(n)—,—(CH₂)_(m)—CO—X—(CH₂)_(n)—O—,

—CH₂—CH(OH)—CH₂—Y—(CH₂)_(m)—, wherein m and n are each independently ofthe other 1-4.

Also preferred are compounds of formula (VIa) or (VIb) wherein S₁, S₂,S₃ and S₄ are each independently of one another hydrogen or methyl.Especially preferred compounds are -(2-hydroxyphenyl)-s-triazines offormula (IaVIaIa) or formula (IbVIbIb) which are substituted in the 4-and 6-position by a phenyl, p-tolyl or 2,4-dimethylphenyl group.

The novel compounds preferably carry at the silicon atom C₁-C₈ alkyl,phenyl or C₁-C₈ alkoxy as substituents S₁₀, S₁₁ and S₁₂, and C₁-C₈ alkylor phenyl as S₁₄, or S₁₀ and/or S₁₁ is a group of formula (VIII).Compounds wherein S₁₀, S₁₁ and S₁₂ are C₁-C₄ alkyl or C₁-C₄ alkoxy andS₁₄ is C₁-C₄ alkyl are especially preferred.

The hydroxyphenyltriazine group is linked to the silyl radical throughthe group S₅.

Preferably S₅ is a group —C_(m)H_(2m)—, —(CH₂)_(m)—O—,—(CH₂)_(m)—CO—X—(CH₂)_(n)—,

or —CH₂—CH(OH)—CH₂—Y—(CH₂)_(m)—, wherein m is 1, 2 or 3, S₇ is methyl,phenyl, C₃-C₉ alkoxymethyl or phenoxymethyl, Se is a group of formulaVII and X and Y are each oxygen.

Particularly preferred compounds of formula VIa or VIb are those whereinS₅ is a group —C_(m)H_(2m)—, —(CH₂)₂—O—, —CH₂—CO—O—CH₂—,—CH₂—CH(O—C₄H₉)—O—,

or —CH₂—CH(OH)—CH₂—O—(CH₂)₃—, m is an integer 1, 2 or 3, and S₈ is aradical

The compounds of formula (ViaVIaVIa), wherein p is 0, are especiallypreferred.

Compounds of formula VIa or VIb, wherein S₁, S₂, S₃ and S₄ are each ino- and/or p-position, p is 0, S₅ is —(CH₂)₃—, S₁₀ is methyl or ethyl,S₁₁ and S₁₂ are ethyl or ethoxy, S₁₄ is methyl, S₁₅ is —OH, methoxy orethoxy, S₁₆ is hydrogen, methyl or ethyl, and, if r is greater than 2,S₁₅ and S₁₆ together may be a direct bond, are also especiallypreferred.

The following compounds are representative examples of compounds offormula ViaVIaVia:

-   -   Z—O—(CH₂)—Si(OCH₃)₃;    -   Z—O—(CH₂)₃—Si(C₄H₉)(OCH)₂;    -   Z—O—(CH₂)₂—O—Si(C₆H₅)(OCH)₂;    -   Z—O—(CH₂)₃—O—CH₂)—Si(CH₃)(OCH₃)₂;    -   Z—O—(CH₂)₂—O—CH₂—Si(OCH₃)₃;    -   Z—O—CH₂COO—(CH₂)—Si(OC₂H₅)₃;    -   Z—O—CH₂CH₂CONH—(CH₂)₃—Si(OC₃H₇)₃;    -   Z—O—CH₂COO—CH₂CH₂O—Si(C₆H₅)(OCH₅)₂;    -   Z—O—CH₂—CH—CH₂OC₄H(O—Si(OCH)₂(CH₃); Z—O—CH₂—CH(OH)—CH₂—    -   O—(CH₂)₃—Si(OCH₃)₂(CH₃)    -   Z—O—CH₂—CH(OH)—CH₂—NH—(CH₂)—Si(OCH₃)₂(CH₃)    -   Z—O—CH₂—CH(OH)—CH₂—N—[(CH₂)—Si(OCH)₂(CH₃)]₂

In the above formula, Z is a group.

Where:

Ar is phenyl, p-tolyl or 2,4-dimethylphenyl.

The synthesis of the compounds of formula IaVIaIa depends on therespective linking group S₅ through which the triazinyl group and thesilyl group are attached. Possible syntheses are set out below for eachtype of S₅.

1) If S₅ is a group —C_(m)H_(2m)—:

AH+Cl—C_(m) H_(2m)—B→IaVIaIa+HCl

Where:

A is a triazine group of formula

and B is a silyl group of formula

An alternative synthesis proceeds according to the scheme:

-   A-(CH₂)_(m-2)—CH═CH₂+HB→VIa

2) If S₅ is a group —(CH₂)_(m)—O—:

-   A-(CH₂)_(m)—OH+Cl—B→VIa+HCl

3) If S₅ is a group —(CH₂)_(m)—O—S₆—:

-   A-(CH₂)_(m)—OH+Cl—S₆—B→VIa+HCl

4) If S₅ is a group —(CH₂)_(m)—CO—X—(CH₂)_(n)—:

-   A-(CH₂)_(m)—COOR+HX—(CH₂)_(n)—B→VIa+ROH-   R═C₁-C₂ alkyl

5) If S₅ is a group —(CH₂)_(m)—CO—X—(CH₂)_(n)—O—:

6) If S₅ is a group

7) If S₅ is a group —CH₂—CH(S₇)—O—:

8) If S₅ is a group —CH₂—CH(OR₈)—CH₂O—:

9) If S₅ is a group

10) If S₅ is a group —CH₂—CH(OH)—CH₂—Y—(CH₂)_(n)—:

Silyl Functional Hindered Amine Light Stabilizers

The invention may pertain to novel compounds of the formula (XI).

Formula (XI):

Where:

m+n is a number from 1 to 100 and n varies from zero to 90% of the sumof m+n,

A is —O— or

Where:

T₆ is hydrogen, C₁-C₁₈ alkyl or a group of the formula (XII)

Formula (XII):

and T₄ which can be identical or different are C₁-C₈ alkyl, phenyl,C₁-C₈ alkoxy, OH, ONa or OK,

T₂ is C₂-C₁₂ alkylene or also a direct bond if A is —O— and T₁ and T₄are C₁-C₈ alkyl or phenyl,

T₃ is C₁-C₁₈ alkyl, C₅-C₁₂ cycloalkyl, C₂-C₁₈ alkenyl, C₅-C₁₂cycloalkenyl, C₇-C₁₂ aralkyl, a saturated or unsaturated radical of abicyclic or tricyclic C₇-C₁₂ hydrocarbon or C₆-C₁₈ aryl which isunsubstituted or substituted by C₁-C₈alkyl,

T₅ is hydrogen, C₁-C₁₈ alkyl, C₅-C₁₂ cycloalkyl or phenyl,

X₁ is as defined for T₁ or is a group (T₇)₃SiO— with T₇ being C₁-C₈alkyl,

X₂ is hydrogen, Na, K, C₁-C₈ alkyl, a group (T₇)₃—Si— or, if n is zeroand T₁ and X₁ are C₁-C₈ alkyl or phenyl, X₂ is also a group of theformula (XIII)

Formula (XIII):

and, if m+n is a number from 3 to 10, X₁ and X₂ together can also be adirect bond.

Each of the groups A, T₁, T₂, T₃, T₄ and T₅ can, in the single recurringunits of the formula (XI), have the same definition or differentdefinitions and, if the compounds of the present invention arecopolymeric, they may have a random distribution or a block distributionof the various recurring units.

Examples of alkyl having not more than 18 carbon atoms are methyl,ethyl, propyl, isopropyl, butyl, 2-butyl, isobutyl, t-butyl, pentyl,2-pentyl, isopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl,decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.

Examples of C₁-C₈ alkoxy are methoxy, ethoxy, propoxy, isopropoxy,butoxy, isobutoxy, t-butoxy, pentoxy, isopentoxy, hexoxy, heptoxy andoctoxy.

Examples of C₅-C₁₂ cycloalkyl are cyclopentyl, cyclohexyl,methylcyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and cyclododecyl.C₅—C₁₂ cycloalkyl also covers a saturated cyclic hydrocarbon radical of5 to 8 carbon atoms, which is substituted by C₁-C₄ alkyl.

Examples of C₂-C₁₈ alkenyl are vinyl, allyl, 2-methylallyl, butenyl,pentenyl, hexenyl, heptenyl, octenyl, decenyl, dodecenyl, tetradecenyl,hexadecenyl and octadecenyl.

Examples of C₅-C₁₂ cycloalkenyl are cyclopentenyl, cyclohexenyl,methylcyclohexenyl, cycloheptenyl, cyclooctenyl, cyclodecenyl andcyclododecenyl. C₅ C₁₂ cycloalkenyl also covers an unsaturated cyclichydrocarbon radical of 5 to 8 carbon atoms, which is substituted byC₁-C₄ alkyl.

Examples of C₇-C₁₂ aralkyl are benzyl, α-methylbenzyl,α,α-dimethylbenzyl and phenylethyl. C₇-C₉ phenylalkyl is preferred.

Examples of saturated or unsaturated radicals of a bicyclic or tricyclicC₇-C₁₂hydrocarbon are bicycloheptyl, bicycloheptenyl, decahydronaphthyl,tetrahydronaphthyl and tricyclodecyl.

Examples of C₅-C₁₀ aryl, which is unsubstituted or substituted by alkylare phenyl, methylphenyl, dimethylphenyl, trimethylphenyl,isopropylphenyl, naphthyl and methylnaphthyl.

Examples of C₂-C₁₂ alkylene are ethylene, propylene, trimethylene,2-methyltrimethylene, tetramethylene, pentamethylene, hexamethylene,octamethylene, decamethylene, undecamethylene and dodecamethylene.Trimethylene is preferred.

Those compounds of the formula (XI) are preferred in which m+n is anumber from 1 to 80, n varies from zero to 90% of the sum m+n, A is —O—or

Where:

T₆ is hydrogen, C₁-C₁₂ alkyl or a group of the formula (XII),

T₁ and T₄ which can be identical or different are C₁-C₆ alkyl, phenyl,C₁-C₆alkoxy, OH, ONa or OK,

T₂ is C₂-C₈ alkylene or also a direct bond if A is —O— and T₁ and T₄ areC₁-C₆ alkyl or phenyl,

T₃ is C₁-C₁₈ alkyl, C₅-C₈ cycloalkyl, C₃-C₁₂ alkenyl, C₅-C₈cycloalkenyl, C₇-C₉ aralkyl, a saturated or unsaturated radical of abicyclic or tricyclic C₇-C₁₀hydrocarbon or C₆-C₁₀ aryl which isunsubstituted or substituted by C₁-C₄alkyl,

T₅ is hydrogen, C₁-C₁₈ alkyl, C₅-C₈ cycloalkyl or phenyl,

X₁ is as defined for R₁ or is a group (T₇)₃SiO— with T₇ being C₁-C₆alkyl,

X₂ is hydrogen, Na, K, C₁-C₆ alkyl, a group (T₇)₃Si— or, if n is zeroand T₁ and X₁ are C₁-C₆ alkyl or phenyl, X₂ is also a group of theformula (XIII) and, if m+n is a number from 3 to 10, X₁ and X₂ togethercan also be a direct bond.

Those compounds of the formula (I) are particularly preferred in whichm+n is a number from 1 to 60, n varies from zero to 90% of the sum ofm+n, A is —O— or

Where:

T₆ is hydrogen or C₁-C₈ alkyl,

T₁ and T₄ which can be identical or different are C₁-C₄ alkyl, phenyl,C₁-C₄alkoxy, OH, ONa or OK,

T₂ is C₂-C₆ alkylene or also a direct bond if A is —O— and T₁ and T₄ areC₁-C₄ alkyl or phenyl,

T₃ is C₁-C₁₆ alkyl, C₅-C₇ cycloalkyl, C₃-C₆ alkenyl, C₅-C₇ cycloalkenyl,benzyl, α-methylbenzyl, α,α-dimethylbenzyl, bicycloheptyl,bicycloheptenyl, decahydronaphthyl or tetrahydronaphthyl,

T₅ is hydrogen, C₁-C₁₆ alkyl, cyclohexyl or phenyl,

X₁ is as defined for R₁ or a group (T₇)₃SiO— with T₇ being C₁-C₄ alkyl,

X₂ is hydrogen, Na, K, C₁-C₄ alkyl, a group (T₇)₃Si— or, if n is zeroand T₁ and X₁ are C₁-C₄ alkyl or phenyl, X₂ is also a group of theformula (XIII) and, if m+n is a number from 3 to 10, X₁ and X₂ togethercan also be a direct bond.

Those compounds of the formula (I) are of special interest in which m+nis a number from 1 to 50, n varies from zero to 75% of the sum m+n, A is—O— or

Where:

T₆ is hydrogen or C₁-C₄ alkyl,

T₁ and T₄ which can be identical or different are C₁-C₃ alkyl, C₁-C₃alkoxy or OH,

T₂ is C₂-C₄ alkylene or is also a direct bond if A is —O— and T₁ and T₄are C₁-C₃ alkyl,

T₃ is methyl, C₆-C₁₂ alkyl, cyclopentyl, cyclohexyl, methylcyclohexyl orα-methylbenzyl,

T₅ is hydrogen, C₁-C₁₄ alkyl or cyclohexyl,

X₁ is as defined for R₁ or is a group (R₇)₃SiO— with T₇ being C₁-C₃alkyl,

X₂ is hydrogen, C₁-C₃ alkyl, a group (R₇)₃Si— or, if n is zero and T₁and X₁ are C₁-C₃ alkyl,

X₂ is also a group of the formula (XIII) and, if m+n is a number from 3to 10, X₁ and X₂ together can also be a direct bond.

Those compounds of the formula (I) are of particular interest in whichm+n is a number from 1 to 40, n varies from zero to 50% of the sum m+n,

A is —O—,

T₁ and T₄ which can be identical or different are methyl, methoxy,ethoxy or OH,

T₂ is trimethylene or is also a direct bond if A is —O— and T₁ and T₄are methyl,

T₃ is methyl, C₇-C₉ alkyl or cyclohexyl,

T₅ is C₁-C₁₂ alkyl,

X₁ is as defined for T₁ or is a group (CH₃)₃SiO— and

X₂ is hydrogen, methyl, ethyl, a group (CH₃)₃Si— or, if n is zero and T₁and X₁ are methyl,

X₂ is also a group of the formula (XIII) and, if m+n is a number from 3to 10, X₁ and X₂ together can also be a direct bond.

The compounds of the present invention may be prepared by variousprocesses known per se.

If T₂ is C₂-C₁₂ alkylene, the compounds of the formula (I) can beprepared, for example, by hydrolytic polycondensation of compounds ofthe formulae (XIVa) and (XIVb).

Formulae (XIVa) and (XIVb):

Where:

G₁ is Cl or C₁-C₈ alkoxy and G₂ is Cl, C₁-C₈ alkoxy or phenyl, asreported, for example, in U.S. Pat. No. 4,946,880, or, if T₁ and T₄ areC₁-C₈ alkyl or phenyl, by reaction of a compound of the formula (XV):

Formula (XV):

with a compound of the formula (XVI)

Formula (XVI):

with T₂′ being C₂-C₁₂ alkenyl, in the presence of catalytic quantitiesof the Pt or Rh complex as described, for example, in U.S. Pat. No.5,051,458 and EP Patent 388 321.

If T₂ is a direct bond, the compounds of the formula (I) can beprepared, for example, by reacting a compound of the formula (V) with apiperidinol of the formula (XVII):

Formula (XVII):

in the presence of catalytic quantifies of a complex of Pt, Rh, or Pd,as described, for example, in U.S. Pat. No. 4,895,885.

The compounds of the formula (XV) are commercially available or can beprepared by known processes. The compounds of the formula (XVI) areprepared, for example, as indicated in U.S. Pat. No. 4,946,880, thegroup T₃O— in the 1-position of the piperidyl group being introducedaccording to the processes disclosed in U.S. Pat. No. 4,921,962.

The compounds of the formula (XVII) are prepared, for example, asreported in U.S. Pat. No. 5,021,481.

Silyl Functional Antioxidants

Silyl functional antioxidant compounds of the present invention may becompounds containing the sterically hindered phenolic group:

Phenolic groups (XVIII) and (XVIIIa):

Where:

S₁ and S₂, which can be equal or different, are preferably branchedalkyl radicals containing from 1 to 10 carbon atoms, and in their mostpreferred form are tert-butyl radicals; said phenolic groups (XVIII) and(XVIIIa) carrying a silyl functionality hydrolysable to silanol. Moreparticularly, the reactive antioxidant compounds of the presentinvention may pertain to the following class of compounds:

Where:

S₁ and S₂ are as heretofore defined; m is zero or one.

T is oxygen or sulfur

A is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or can be defined by means of

(where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms);

X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical.

Y is hydrogen, halogen and preferably chlorine, C₁-C₄ acyloxy, C₁-C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁-C₂ alkyloxy.

n is one, two or three.

Specific examples of reactive antioxidant compounds which fall withinformula (XIX) are the following:

Formulae (XX) and (XXI):

The reactive antioxidant compounds (XX) and (XXI) and can be obtainedfrom the compound (XXII):

Compound (XXII):

by hydrosilylation with methyldimethoxysilane, andg-mercaptopropyltrimethoxysilane respectively. A further specificexample of a reactive antioxidant compound falling within formula (XIX)is the following:

The reactive antioxidant compound above can be obtained byhydrosilylation of the compound:

with methyldimethoxysilane.

A further example of a reactive antioxidant compound falling withingeneral formula (XIX) is the following:

The reactive antioxidant compound above can be obtained byhydrosilylation with methyldimethoxy silane of the compound:

In general, the reactive antioxidant compounds of the present inventionmay be prepared by silylating a sterically hindered phenol carrying onits ring a preferably terminal ethylenically unsaturated group or bysubjecting said ethylenically unsaturated group to alkenehydrothiolation.

One class of hydrosilylation agents suitable for this purpose isdefinable by the formula (XXIII):

Formula (XXIII):

A class of hydrothiolation agents suitable for the purpose is definableby the general formula (XXIV):

Formula (XXIV):

Where:

S₅, X, Y and n have the aforesaid meanings.

Specific examples of hydrosilylation agents falling within generalformula (XXIII) are:

-   -   HSi(OCH₃)₂C; HSi(OCH₃)Cl₂; HSiCl₃;    -   HSi(OCH₃)₂(CH₃); HSi(CH₃)(OC₂H₅)₂;    -   HSi(OC₂H₅)₃; H₂Si(C₂H₅)₂;    -   HSi(OCH₃)₃; HSi(CH₃)₂—O—Si(CH₃)₂H;    -   HSi(CH₃)₂—O—Si(CH₃)(OCH₃)₂;    -   HSi(CH₃)₂ONC(CH₃)₂;    -   HSi(CH₃)[ONC(CH₃)₂]₂

Specific examples of hydrothiolation agents which fall within generalformula (XXIV) are γ-mercaptopropyltrialkoxysilanes and in particularg-mercaptopropyltrimethoxysilane.

The hydrosilylation reaction is conveniently conducted at a temperatureof between 0° and 200° C., and preferably between ambient temperature(20°−25° C.) and 120° C., with a reagent quantity varying fromstoichiometric to an excess of the hydrosilylation reagent. Said excessusually reaches up to 20% on a molar basis. However, if disilanes areused it is convenient to use a large excess of the hydrosilylationagent, for example up to about 10 times the stoichiometric quantity. Thehydrosilylation reaction is catalyzed by metal catalysts, by ultravioletradiation and by radical initiators. The preferred catalysts areplatinum compounds and complexes of platinum with olefins, preferablychloroplatinic acid. In the case of platinum catalysts, the catalystconcentration, evaluated as metal, can vary from 1 to 200 parts permillion and preferably from 5 to 50 parts per million in the reactionmedium.

The hydrosilylation reaction can be conducted in an inert (unreactive)organic solvent, normally chosen from aliphatic, cycloaliphatic, andaromatic hydrocarbons and ethers, which are liquid under the operatingconditions. Specific examples of solvents suitable for this purpose areheptane, cyclohexane, toluene, tetrahydrofuran, dioxane anddimethoxyethane. The reaction times depend on the reagents used and thereaction temperature and vary normally from 0.5 to 10 hours. Ontermination of the hydrosilylation reaction, any solvent used, and anyexcess hydrosilylation agent are removed by stripping, and the reactivestabilizing compound is recovered from the residue of said stripping bynormal methods such as crystallization and distillation under vacuum.However, generally the high yield and selectivity of the hydrosilylationreaction make any separation or purification of the final requiredproduct unnecessary. If hydrosilylation compounds falling within formula(XXIV) are used, the reaction is conveniently conducted under theaforesaid general hydrosilylation conditions with catalysts in the formof azo compounds such as azobisisobutyronitrile, which are used in aquantity of between 0.1% and 10% and preferably between 0.5% and 2% inthe reaction environment. The reactive antioxidant compounds of thepresent invention may hydrolyze at the silyl function under mildconditions, to generate silanol groups which can be condensed togetherto form complex resinous stabilizing structures. These resinousstructures, of silicone resin type, preserve the inherent stabilizingcharacteristics of sterically hindered phenols, and have a high level ofcompatibility with organic polymers, and practically no extractabilityfrom said polymers. Hydrolysis at the silyl function takes place simplyby contact with water or with environmental moisture at ambienttemperature (20°−25° C.) or lower than ambient. Condensation between thesilanol groups to give the complex resinous structures can befacilitated by acid or basic agents, soaps, or metal esters, andorganometal compounds, especially of lead and tin. Preferred catalystsfor this purpose are tin dibutyl tin dilaurate, and strong sulfonicacids such as dodecyl benzenesulfonic acid. Conveniently, the catalystquantity can vary from 0.1% to 10% by weight and preferably from 0.2% to3% by weight with respect to the reactive antioxidant compound subjectedto resinification. Said resinification reaction can be conducted atambient temperature (20°−25° C.) or at higher or lower than ambient. Thecomplex resinous structures thus obtained can be introduced into theorganic polymer to be stabilized by the usual methods used for thispurpose. According to a further embodiment of the present invention, thereactive antioxidant compounds may be introduced directly into theorganic polymer, within which the hydrolysis reaction at the silylfunction and the interaction between the silanol groups take placespontaneously, to thus give the stabilized polymer composition.According to a further embodiment, hydrolysis at the silyl function ofthe reactive antioxidant compounds takes place externally to thepolymer, together with partial resinification of the hydrolysis productsthus obtained. The product of the partial resinification is thenintroduced into the organic polymer to be stabilized, within whichcomplete resinification takes place.

Silyl Functional Ferrocene Derivatives

Silyl functional ferrocenes of the present invention are novel compoundscontaining the ferrocene moiety

carrying a silyl function hydrolysable to silanol. More particularly,the reactive ferrocene compounds of the present invention may pertain tothe following class of compounds:

m is 1-4, with up to four functional silane groups attached to everyferrocene moiety.

A is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or can be defined by means of

(where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms);

X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical.

Y is hydrogen, halogen and preferably chlorine, C₁-C₄ acyloxy, C₁-C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁-C₂ alkyloxy.

n is one, two or three.

Specific examples of reactive ferrocene compounds are the following:

The ferrocene compounds of the current invention may be prepared by thehydrosilylation of the corresponding vinyl or allyl ferrocene. One classof hydrosilylation agents suitable for this purpose is definable by theformula:

Specific examples of hydrosilylation agents falling within this generalformula include:

-   -   HSi(CH₃)₂Cl; HSi(CH₃)Cl₂; HSiCl₃;    -   HSi(OCH₃)₂(CH₃); HSi(CH₃)(OC₂H₅)₂;    -   HSi(OC₂H₅)₃; H₂Si(C₂H₅)₂;    -   HSi(OCH₃)₃; HSi(CH₃)₂—O—Si(CH₃)₂H;    -   HSi(CH₃)₂—O—Si(CH₃)(OCH₃)₂;    -   HSi(CH₃)₂ONC(CH₃)₂;    -   HSi(CH₃)[ONC(CH₃)₂]₂

Particular preferred aspects of the Invention can be understood by thefollowing clauses:

1. A method for extending the useful life of an insulated cable,comprising injecting, into a cable having a stranded conductor encasedin a polymeric insulation jacket, a dielectric gel formulationcontaining: (a) an Si—H endblocked polydiorganosiloxane fluid with theformula H(R₂SiO)_(x)(R₂Si)H and having a viscosity of 0.5 to about 100centistokes at 25° C.; (b) a polydiorganosiloxane fluid endblocked withgroups containing unsaturated carbon-carbon functionality and having aviscosity of 0.5 to about 100 centistokes at 25° C.; (c) hydrosilylationcatalyst suitable to cure the mixture of parts (a) and (b); and (d) atleast one organoalkoxysilane functional additive selected from (i) ananti-oxidant-based alkoxysilane (e.g., hindered phenolic additives basedon 2,6-di-tert-butyl phenol derived products), (ii) a voltagestabilizer-based alkoxysilane (e.g., metallocene-based alkoxysilane,(iii) a hindered amine light stabilizer (HALS)-based alkoxylsilane(e.g., tetramethyl piperidine-based alkoxysilane), and/or (iv) a UVabsorber-based alkoxysilane (e.g., benzotriazole-based, triazine-based,nickel chelate-based), and wherein, after injection, the mixture ofparts (a) and (b) is cured into a non-flowable gel in the cable, andwherein the at least one functional additive diffuses into the polymericinsulation.

2. The method of clause 1, wherein in the methods, the formulation mayfurther comprise one or more siloxane crosslinkers.

3. The method of clauses 1 or 2, wherein in the methods, the formulationmay further comprise one or more hydrolysis/condensation catalystsuitable to catalyze hydrolysis and condensation of the at least onefunctional additive of (d).

4. The method of clause 3, wherein in the methods, thehydrolysis/condensation catalyst may be compatible with thehydrosilylation catalyst so as not to interfere with the cure of the gelformulation containing (a), (b) and (c), and/or may be compatible withoptional siloxane crosslinker, and optional hydrosilylation inhibitor.

5. The method of clause 4, wherein in the methods, thehydrolysis/condensation catalyst is one or more selected fromorganometallic compounds of tin, manganese, iron, cobalt, nickel, lead,titanium, or zirconium, including but not limited to alkyl titanates,acyl titanates and the corresponding zirconates, tetra-t-butyl titanate(TBT), dibutyltindiacetate (DBTDA), dibutyltindilaurate (DBTDL),dibutyltindioleate, tetraethylorthotitanate, tetraisopropyl titanate(TIPT), tetraoctadecylorthotitanate, dibutyltindioctoate, stannousoctoate, dimethyltinneodeconoate, di-N-octyltin-S,S-isooctylmercaptoacetate, dibutyltin-S, S-dimethylmercaptoacetate,and/or diethyltin-S,S-dibutylmercaptoacetate.

6. The method of clause 5, wherein in the methods, thehydrolysis/condensation catalyst may be added at a level of about 0.05to about 5% based on the total weight of the organoalkoxysilanecomponents, or supplied at a level of about 0.1 to about 2% or at alevel of about 0.2 to 1% by weight according to the above-mentionedbasis.

7. The method of any one of clauses 1-6, wherein in the methods, theformulation may further comprise a hydrosilylation inhibitor.

8. The method of any one of clauses 1-6, wherein in the methods, theformulation may further comprise at least two components selected fromsiloxane crosslinker components, hydrolysis/condensation catalystcomponents, and hydrosilylation inhibitor components.

9. The method of any one of clauses 2-8, wherein in the methods, thecrosslinker may be a siloxane polymer containing both terminal andpendant Si—H groups.

10. The method of any one of clauses 3-9, wherein in the methods, thehydrolysis/condensation catalyst may be titanium(IV) isopropoxide.

11. The method of any one of clauses 7-10, wherein in the methods, thehydrosilylation inhibitor may be a dialkyl maleate.

12. The method of any one of clauses 1-11, wherein in the methods, theformulation may cure to a non-flowable gel in less than 48 hrs at 35 C.

13. The method of any one of clauses 1-12, wherein in the methods, theformulation may have a time to viscosity doubling of at least 4 hours at35 C.

14. The method of any one of clauses 1-13, wherein in the methods, theformulation may cure after injection to a non-flowable gel in less than48 hrs at 35 C.

15. The method of any one of clauses 1-14, wherein in the methods, theformulation may have a time to viscosity doubling after injection of atleast 4 hours at 35 C.

16. The method of any one of clauses 1-15, wherein in the methods, theformulation may have an initial viscosity after injection of <10 cP.

17. The method of any one of clauses 1-16, wherein in the methods, theformulation may have an initial viscosity after injection of <10 cP.

18. The method of any one of clauses 1-17, wherein in the methods, forthe Si—H endblocked polydiorganosiloxane of formula H(R₂SiO)_(x)(R₂Si)H,R may be selected from alkyl radicals having 1 to 6 carbon atoms or thephenyl radical; preferably a methyl radical.

19. The method of any one of clauses 1-18, wherein in the methods, theSi—H endblocked polydiorganosiloxane may have an average x valueselected from 1 to 40, 1 to 20, or 1 to 10.

20. The method of any one of clauses 1-19, wherein thepolydiorganosiloxane may be represented by the formula

-   -   R″ R″    -   G-(SiO)_(y)—Si-G    -   R″ R″        wherein G denotes unsaturated radicals independently selected        from the vinyl group or higher alkenyl radicals represented by        the formula-R′″(CH₂)_(m)CH═=CH₂, in which R′″ denotes        —(CH₂CH₂CH₂)— or —(CH₂CH₂CH₂)_(q)CH═CH—, m is 1, 2. or 3. p is 3        or 6 and q is 3. 4 or 5, R″ is independently selected from an        alkyl radical having 1 to 6 carbon atoms or a phenyl radical;        preferably a methyl radical, and y has an average value selected        from 1 to about 40, 1 to 20, or 1 to 10.

21. The method of any one of clauses 1-20, wherein in the methods, thehydrosilylation catalyst may comprise a platinum compound.

22. The method of clause 21, wherein in the methods, the platinumcompound may comprise platinum(tetramethyldivinylsiloxane).

23. The method of any one of clauses 1-22, wherein components (a) and(b) may be contained in a first part of the formulation and then may bemixed with a second part of the formulation containing components (c)and (d).

24. The method of any one of clauses 8-22, wherein components (a), (b),the optional crosslinker, and the optional inhibitor are contained in afirst part of the formulation and components (c), (d), and the optionalhydrolysis/condensation catalyst are contained in a second part of theformulation, and wherein the first and second parts are mixed togetherimmediately prior to injection.

25. The method of any one of clauses 1-24, wherein in the methods, thesilane functional additives may have a PE retention of at least 0.2%.

26. The method of any one of clauses 1-25, wherein in the methods, theat least one silane functional additive may permeate into the cableinsulation reaching at least 90% of saturation in less than 500 hours at55° C.

27. The method of any one of clauses 1-26, wherein in the methods, theat least one silane-functional additive may have a diffusivity in PEgreater than 5.0×10-cm²/s at 55° C. and a PE retention of at least 0.40wt % at 5,000 hours at 55° C.

The foregoing described embodiments depict different componentscontained within, or connected with, different other components. It isto be understood that such depicted architectures are merely exemplary,and that in fact many other architectures can be implemented whichachieve the same functionality. In a conceptual sense, any arrangementof components to achieve the same functionality is effectively“associated” such that the desired functionality is achieved. Hence, anytwo components herein combined to achieve a particular functionality canbe seen as “associated with” each other such that the desiredfunctionality is achieved, irrespective of architectures or intermedialcomponents. Likewise, any two components so associated can also beviewed as being “operably connected,” or “operably coupled,” to eachother to achieve the desired functionality.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art that,based upon the teachings herein, changes and modifications may be madewithout departing from this invention and its broader aspects and,therefore, the appended claims are to encompass within their scope allsuch changes and modifications as are within the true spirit and scopeof this invention. Furthermore, it is to be understood that theinvention is solely defined by the appended claims. It will beunderstood by those within the art that, in general, terms used herein,and especially in the appended claims (e.g., bodies of the appendedclaims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations).

Conjunctive language, such as phrases of the form “at least one of A, B,and C,” or “at least one of A, B and C,” (i.e., the same phrase with orwithout the Oxford comma) unless specifically stated otherwise orotherwise clearly contradicted by context, is otherwise understood withthe context as used in general to present that an item, term, etc., maybe either A or B or C, any nonempty subset of the set of A and B and C,or any set not contradicted by context or otherwise excluded thatcontains at least one A, at least one B, or at least one C. Forinstance, in the illustrative example of a set having three members, theconjunctive phrases “at least one of A, B, and C” and “at least one ofA, B and C” refer to any of the following sets: {A}, {B}, {C}, {A, B},{A, C}, {B, C}, {A, B, C}, and, if not contradicted explicitly or bycontext, any set having {A}, {B}, and/or {C} as a subset (e.g., setswith multiple “A”). Thus, such conjunctive language is not generallyintended to imply that certain embodiments require at least one of A, atleast one of B, and at least one of C each to be present. Similarly,phrases such as “at least one of A, B, or C” and “at least one of A, Bor C” refer to the same as “at least one of A, B, and C” and “at leastone of A, B and C” refer to any of the following sets: {A}, {B}, {C},{A, B}, {A, C}, {B, C}, {A, B, C}, unless differing meaning isexplicitly stated or clear from context.

Accordingly, the invention is not limited except as by the appendedclaims.

The invention claimed is:
 1. A method for extending the useful life ofin-service electrical cable, comprising injecting a dielectricenhancement fluid composition into at least one section of an electricalcable having a stranded conductor encased in a polymeric insulationjacket, and having an average operating temperature T, the compositioncomprising: (a) at least one organoalkoxysilane functional additiveselected from (i) a voltage stabilizer-based alkoxysilane (e.g.,metallocene-based alkoxysilane, (ii) a hindered amine light stabilizer(HALS)-based alkoxylsilane (e.g., tetramethyl piperidine-basedalkoxysilane), and/or (iii) a UV absorber-based alkoxysilane (e.g.,benzotriazole-based, triazine-based, nickel chelate-based); and (b) atleast one catalyst suitable to catalyze hydrolysis and condensation ofthe at least one functional additive of (a), and wherein the injectedcomposition provides for both initial permeation of the at least onefunctional additive into the polymeric insulation, and extendedretention of subsequent condensation products of the at least onefunctional additive in the cable insulation.
 2. The method of claim 1,wherein the cable section has a stranded conductor surrounded by aconductor shield encased in a polymeric insulation jacket with an outerinsulation shield, and having an interstitial void volume in the regionof the conductor, and wherein injecting comprises injecting thedielectric enhancement fluid composition into the interstitial voidvolume, and/or into the space between the polymeric insulation jacketand the outer insulation shield.
 3. The method of claim 1, wherein thedielectric enhancement fluid composition further comprises (c) at leastone water-reactive organosilane material selected from (i) anorganosilane monomer having at least two water-reactive groups, (ii) theorganosilane monomer (i) where at least one of the water-reactive groupsis substituted with a condensable silanol group, (iii) an oligomer ofthe above organosilane monomer (i), and/or (iv) a co-oligomer of theabove organosilane monomer (i) with a different organosilane monomer,and wherein the catalyst provides for covalent binding of the at leastone functional additive of (a) to the at least one water-reactivematerial (c) upon hydrolysis and condensation thereof.
 4. The method ofclaim 3, wherein the organosilane monomer (i) has a diffusioncoefficient at least about 15 times greater than the diffusioncoefficient of its corresponding tetramer, the diffusion coefficientbeing determined at the average operating temperature T of the at leastone section of the in-service electrical cable.
 5. The method of claim3, wherein the dielectric enhancement fluid composition furthercomprises: (d) a non-water-reactive organic material which has adiffusion coefficient of less than about 10⁻⁹ cm²/sec and an equilibriumconcentration of at least about 0.005 gm/cm³ in said polymericinsulation, the diffusion coefficient and the equilibrium concentrationbeing determined at the average operating temperature T; and/or (e) anorganic compound having an equilibrium concentration in the polymericinsulation at 55° C. which is less than 2.25 times the equilibriumconcentration at 22° C.
 6. The method of claim 4, wherein the dielectricenhancement fluid composition further comprises: (d) anon-water-reactive organic material which has a diffusion coefficient ofless than about 10⁻⁹ cm²/sec and an equilibrium concentration of atleast about 0.005 gm/cm³ in said polymeric insulation, the diffusioncoefficient and the equilibrium concentration being determined at theaverage operating temperature T; and/or (e) an organic compound havingan equilibrium concentration in the polymeric insulation at 55° C. whichis less than 2.25 times the equilibrium concentration at 22° C.
 7. Themethod of claim 3, wherein the at least one water-reactive organosilanematerial is/are organoalkoxysilanes.
 8. The method of claim 7, whereinthe organoalkoxysilanes are selected from:(3-methylphenyl)methyldimethoxysilane,di(4-methylphenyl)dimethoxysilane, dimethyldi-n-butoxysilane(4-methylphenyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane 3-cyanobutylmethyldimethoxysilanephenethyltrimethoxysilane, p-tolylethyl)methyldimethoxysilane,(p-styrylethyl)trmethoxysilane, phenylmethyldimethoxysilane3-(2,4-dinitrophenylamino)propyltriethoxysilane, or3-(triethoxysilylpropyl) p-nitrobenzamide.
 9. The method of claim 8,wherein the organoalkoxysilanes are (p-tolylethyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane, dimethyldi-n-butoxysilane, or3-cyanobutylmethyldimethoxysilane.
 10. The method of claim 4, whereinthe at least one water-reactive organosilane material is/areorganoalkoxysilanes.
 11. The method of claim 10, wherein theorganoalkoxysilanes are selected from:(3-methylphenyl)methyldimethoxysilane,di(4-methylphenyl)dimethoxysilane, dimethyldi-n-butoxysilane(4-methylphenyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane 3-cyanobutylmethyldimethoxysilanephenethyltrimethoxysilane, p-tolylethyl)methyldimethoxysilane,(p-styrylethyl)trimethoxysilane, phenylmethyldimethoxysilane3-(2,4-dinitrophenylamino)propyltriethoxysilane, or3-(triethoxysilylpropyl) p-nitrobenzamide.
 12. The method of claim 11,wherein the organoalkoxysilanes are (p-tolylethyl)methyldimethoxysilane,3-cyanopropylmethyldimethoxysilane, dimethyldi-n-butoxysilane, or3-cyanobutylmethyldimethoxysilane.
 13. The method of claim 1, whereinthe organoalkoxysilane functional additives are derived from at leastone of the following stabilizing functionalities; hydroxyphenylbenzotriazole chromophores hydroxyphenyl triazine chromophores N-Alkoxy2,2,6,6-tetramethyl piperidine light stabilizers ferrocene backbones.14. The method of claim 13 wherein the at least one functional additiveis a compound of Formula 1

wherein, m is 1-4; A is a linear or branched alkylene radical containingfrom 1 to 10 carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms; X is a linear or branchedalkyl radical containing from 1 to 5 carbon atoms, and preferably themethyl radical; Y is hydrogen, halogen and preferably chlorine, C₁-C₄acyloxy, C₁-C₄ alkyloxy, amino, amino-oxy or silyloxy, and preferablyC₁-C₂ alkyloxy; and n is one, two or three.
 15. The method of claim 14wherein the functional additive is an organoalkoxysilane compoundselected from


16. The method of claim 1, wherein the composition further comprises anorganoalkoxysilane functional additive derived from a hindered phenolicantioxidant backbone.
 17. The method of claim 1, where the at least oneorganoalkoxysilane functional additive has in PE retention of at least0.2%.
 18. The method of claim 1, where the at least oneorganoalkoxysilane functional additive permeates into the cableinsulation reaching at least 90% of saturation in less than 500 hours at55° C.
 19. The method of claim 1, where the at least oneorganoalkoxysilane functional additive has a diffusivity in PE greaterthan 5.0×10⁻⁹ cm²/s at 55° C. and a PE retention of at least 0.40 wt %at 5,000 hours at 55° C.
 20. A method for extending the useful life ofin-service electrical cable, comprising injecting a dielectricenhancement fluid composition into at least one section of an electricalcable having a stranded conductor encased in a polymeric insulationjacket, and having an average operating temperature T, the compositioncomprising: (a) at least one functional additive selected from acompound of Formula 1

wherein, m is 1-4; A is a linear or branched alkylene radical containingfrom 1 to 10 carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms; X is a linear or branchedalkyl radical containing from 1 to 5 carbon atoms, and preferably themethyl radical; Y is hydrogen, halogen and preferably chlorine, C₁-C₄acyloxy, C₁-C₄ alkyloxy, amino, amino-oxy or silyloxy, and preferablyC₁-C₂ alkyloxy; and n is one, two or three; and (b) at least onecatalyst suitable to catalyze hydrolysis and condensation of the atleast one functional additive of (a), and wherein the injectedcomposition provides for both initial permeation of the at least onefunctional additive into the polymeric insulation, and extendedretention of subsequent condensation products of the at least onefunctional additive in the cable insulation.
 21. The method of claim 20,wherein the functional additive is an organoalkoxysilane compoundselected from


22. The method of claim 20, wherein the cable section has a strandedconductor surrounded by a conductor shield encased in a polymericinsulation jacket with an outer insulation shield, and having aninterstitial void volume in the region of the conductor, and whereininjecting comprises injecting the dielectric enhancement fluidcomposition into the interstitial void volume, and/or into the spacebetween the polymeric insulation jacket and the outer insulation shield.23. The method of claim 20, wherein the dielectric enhancement fluidcomposition further comprises (c) at least one water-reactiveorganosilane material selected from (i) an organosilane monomer havingat least two water-reactive groups, (ii) the organosilane monomer (i)where at least one of the water-reactive groups is substituted with acondensable silanol group, (iii) an oligomer of the above organosilanemonomer (i), and/or (iv) a co-oligomer of the above organosilane monomer(i) with a different organosilane monomer, and wherein the catalystprovides for covalent binding of the at least one functional additive of(a) to the at least one water-reactive material (c) upon hydrolysis andcondensation thereof.
 24. A compound of Formula 1

wherein, m is 1-4; A is a linear or branched alkylene radical containingfrom 1 to 10 carbon atoms, or one of

where S₃, S₄ and S₅ are linear or branched alkylene radicals containinga total of between 3 and 10 carbon atoms; X is a linear or branchedalkyl radical containing from 1 to 5 carbon atoms, and preferably themethyl radical; Y is hydrogen, halogen and preferably chlorine, C₁-C₄acyloxy, C₁-C₄ alkyloxy, amino, amino-oxy or silyloxy, and preferablyC₁-C₂ alkyloxy; and n is one, two or three.
 25. The compound of claim24, wherein the compound is selected from